From 151ab5c4b7c79b1c31b5b0078552b2e587b8df24 Mon Sep 17 00:00:00 2001
From: alexander-akait <sheo13666q@gmail.com>
Date: Wed, 28 Jan 2026 15:48:40 +0300
Subject: [PATCH 1/3] refactor: more ES6 code and code improvements

---
 client/components/Button.jsx           |  9 +--
 client/components/Checkbox.jsx         | 10 +--
 client/components/CheckboxList.jsx     | 11 +--
 client/components/CheckboxListItem.jsx |  9 +--
 client/components/ContextMenu.jsx      | 26 +++----
 client/components/ContextMenuItem.jsx  |  7 +-
 client/components/Dropdown.jsx         | 12 ++--
 client/components/Icon.jsx             |  8 +--
 client/components/ModuleItem.jsx       | 21 +++---
 client/components/ModulesList.jsx      |  9 +--
 client/components/ModulesTreemap.jsx   | 79 +++++++++++-----------
 client/components/Search.jsx           | 17 ++---
 client/components/Sidebar.jsx          | 38 ++++++-----
 client/components/Switcher.jsx         | 13 ++--
 client/components/SwitcherItem.jsx     |  4 +-
 client/components/ThemeToggle.jsx      | 13 ++--
 client/components/Tooltip.jsx          |  9 +--
 client/components/Treemap.jsx          |  8 +--
 client/localStorage.js                 |  6 +-
 client/store.js                        | 25 ++++---
 client/utils.js                        |  6 +-
 client/viewer.jsx                      |  7 +-
 jest.config.js                         |  2 +
 src/BundleAnalyzerPlugin.js            | 14 ++--
 src/Logger.js                          | 12 ++--
 src/analyzer.js                        | 47 +++++++------
 src/bin/analyzer.js                    | 48 ++++++-------
 src/parseUtils.js                      | 19 +++---
 src/sizeUtils.js                       |  2 +-
 src/statsUtils.js                      |  9 ++-
 src/template.js                        | 14 ++--
 src/tree/BaseFolder.js                 | 25 ++++---
 src/tree/ConcatenatedModule.js         | 14 ++--
 src/tree/Folder.js                     | 10 +--
 src/tree/Module.js                     |  2 +-
 src/utils.js                           | 28 ++++----
 src/viewer.js                          | 54 ++++++++-------
 test/Logger.js                         | 20 +++---
 test/analyzer.js                       | 93 +++++++++++++-------------
 test/dev-server.js                     | 24 ++++---
 test/dev-server/webpack.config.js      |  7 +-
 test/helpers.js                        | 13 ++--
 test/parseUtils.js                     | 33 ++++-----
 test/plugin.js                         | 68 ++++++++++---------
 test/statsUtils.js                     | 49 +++++++-------
 test/utils.js                          | 14 ++--
 test/viewer.js                         | 24 +++----
 webpack.config.js                      | 10 +--
 48 files changed, 529 insertions(+), 473 deletions(-)

diff --git a/client/components/Button.jsx b/client/components/Button.jsx
index bd8057e7..9f2ed889 100644
--- a/client/components/Button.jsx
+++ b/client/components/Button.jsx
@@ -1,12 +1,13 @@
 import cls from "classnames";
-import * as s from "./Button.css";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+
+import * as styles from "./Button.css";
 
 export default class Button extends PureComponent {
   render({ active, className, children, ...props }) {
     const classes = cls(className, {
-      [s.button]: true,
-      [s.active]: active,
+      [styles.button]: true,
+      [styles.active]: active,
     });
 
     return (
diff --git a/client/components/Checkbox.jsx b/client/components/Checkbox.jsx
index 3f1902b7..be2c1ed3 100644
--- a/client/components/Checkbox.jsx
+++ b/client/components/Checkbox.jsx
@@ -1,21 +1,21 @@
-import { Component } from "preact";
 import cls from "classnames";
+import { Component } from "preact";
 
-import * as s from "./Checkbox.css";
+import * as styles from "./Checkbox.css";
 
 export default class Checkbox extends Component {
   render() {
     const { checked, className, children } = this.props;
 
     return (
-      <label className={cls(s.label, className)}>
+      <label className={cls(styles.label, className)}>
         <input
-          className={s.checkbox}
+          className={styles.checkbox}
           type="checkbox"
           checked={checked}
           onChange={this.handleChange}
         />
-        <span className={s.itemText}>{children}</span>
+        <span className={styles.itemText}>{children}</span>
       </label>
     );
   }
diff --git a/client/components/CheckboxList.jsx b/client/components/CheckboxList.jsx
index dd15a0a8..3b5a14ad 100644
--- a/client/components/CheckboxList.jsx
+++ b/client/components/CheckboxList.jsx
@@ -1,6 +1,7 @@
-import CheckboxListItem from "./CheckboxListItem";
-import * as s from "./CheckboxList.css";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+import CheckboxListItem from "./CheckboxListItem.jsx";
+
+import * as styles from "./CheckboxList.css";
 
 const ALL_ITEM = Symbol("ALL_ITEM");
 
@@ -40,8 +41,8 @@ export default class CheckboxList extends PureComponent {
     const { label, items, renderLabel } = this.props;
 
     return (
-      <div className={s.container}>
-        <div className={s.label}>{label}:</div>
+      <div className={styles.container}>
+        <div className={styles.label}>{label}:</div>
         <div>
           <CheckboxListItem
             item={ALL_ITEM}
diff --git a/client/components/CheckboxListItem.jsx b/client/components/CheckboxListItem.jsx
index 69a2526a..4ce8401b 100644
--- a/client/components/CheckboxListItem.jsx
+++ b/client/components/CheckboxListItem.jsx
@@ -1,13 +1,14 @@
 import { Component } from "preact";
 
-import Checkbox from "./Checkbox";
-import CheckboxList from "./CheckboxList";
-import * as s from "./CheckboxList.css";
+import Checkbox from "./Checkbox.jsx";
+import CheckboxList from "./CheckboxList.jsx";
+
+import * as styles from "./CheckboxList.css";
 
 export default class CheckboxListItem extends Component {
   render() {
     return (
-      <div className={s.item}>
+      <div className={styles.item}>
         <Checkbox {...this.props} onChange={this.handleChange}>
           {this.renderLabel()}
         </Checkbox>
diff --git a/client/components/ContextMenu.jsx b/client/components/ContextMenu.jsx
index 13dd5339..d4542f93 100644
--- a/client/components/ContextMenu.jsx
+++ b/client/components/ContextMenu.jsx
@@ -1,10 +1,10 @@
 import cls from "classnames";
-import ContextMenuItem from "./ContextMenuItem";
-import PureComponent from "../lib/PureComponent";
-import { store } from "../store";
-import { elementIsOutside } from "../utils";
+import PureComponent from "../lib/PureComponent.jsx";
+import { store } from "../store.js";
+import { elementIsOutside } from "../utils.js";
+import ContextMenuItem from "./ContextMenuItem.jsx";
 
-import * as s from "./ContextMenu.css";
+import * as styles from "./ContextMenu.css";
 
 export default class ContextMenu extends PureComponent {
   componentDidMount() {
@@ -30,8 +30,8 @@ export default class ContextMenu extends PureComponent {
   render() {
     const { visible } = this.props;
     const containerClassName = cls({
-      [s.container]: true,
-      [s.hidden]: !visible,
+      [styles.container]: true,
+      [styles.hidden]: !visible,
     });
     const multipleChunksSelected = store.selectedChunks.length > 1;
     return (
@@ -93,14 +93,14 @@ export default class ContextMenu extends PureComponent {
   /**
    * Handle document-wide `mousedown` events to detect clicks
    * outside the context menu.
-   * @param {MouseEvent} e - DOM mouse event object
+   * @param {MouseEvent} event - DOM mouse event object
    * @returns {void}
    */
-  handleDocumentMousedown = (e) => {
-    const isSecondaryClick = e.ctrlKey || e.button === 2;
-    if (!isSecondaryClick && elementIsOutside(e.target, this.node)) {
-      e.preventDefault();
-      e.stopPropagation();
+  handleDocumentMousedown = (event) => {
+    const isSecondaryClick = event.ctrlKey || event.button === 2;
+    if (!isSecondaryClick && elementIsOutside(event.target, this.node)) {
+      event.preventDefault();
+      event.stopPropagation();
       this.hide();
     }
   };
diff --git a/client/components/ContextMenuItem.jsx b/client/components/ContextMenuItem.jsx
index cd7cf7ee..d44f398b 100644
--- a/client/components/ContextMenuItem.jsx
+++ b/client/components/ContextMenuItem.jsx
@@ -1,5 +1,6 @@
 import cls from "classnames";
-import * as s from "./ContextMenuItem.css";
+
+import * as styles from "./ContextMenuItem.css";
 
 function noop() {
   return false;
@@ -7,8 +8,8 @@ function noop() {
 
 export default function ContextMenuItem({ children, disabled, onClick }) {
   const className = cls({
-    [s.item]: true,
-    [s.disabled]: disabled,
+    [styles.item]: true,
+    [styles.disabled]: disabled,
   });
   const handler = disabled ? noop : onClick;
   return (
diff --git a/client/components/Dropdown.jsx b/client/components/Dropdown.jsx
index 4bc3dcb7..141a3cd8 100644
--- a/client/components/Dropdown.jsx
+++ b/client/components/Dropdown.jsx
@@ -1,7 +1,7 @@
 import { createRef } from "preact";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
 
-import * as s from "./Dropdown.css";
+import * as styles from "./Dropdown.css";
 
 export default class Dropdown extends PureComponent {
   input = createRef();
@@ -29,12 +29,12 @@ export default class Dropdown extends PureComponent {
       : options;
 
     return (
-      <div className={s.container}>
-        <div className={s.label}>{label}:</div>
+      <div className={styles.container}>
+        <div className={styles.label}>{label}:</div>
         <div>
           <input
             ref={this.input}
-            className={s.input}
+            className={styles.input}
             type="text"
             value={this.state.query}
             onInput={this.handleInput}
@@ -45,7 +45,7 @@ export default class Dropdown extends PureComponent {
               {filteredOptions.map((option) => (
                 <div
                   key={option}
-                  className={s.option}
+                  className={styles.option}
                   onClick={this.getOptionClickHandler(option)}
                 >
                   {option}
diff --git a/client/components/Icon.jsx b/client/components/Icon.jsx
index 3fe4a4b8..9d73e0eb 100644
--- a/client/components/Icon.jsx
+++ b/client/components/Icon.jsx
@@ -1,11 +1,11 @@
 import cls from "classnames";
-import * as s from "./Icon.css";
-import PureComponent from "../lib/PureComponent";
-
 import iconArrowRight from "../assets/icon-arrow-right.svg";
-import iconPin from "../assets/icon-pin.svg";
 import iconMoon from "../assets/icon-moon.svg";
+import iconPin from "../assets/icon-pin.svg";
 import iconSun from "../assets/icon-sun.svg";
+import PureComponent from "../lib/PureComponent.jsx";
+
+import * as s from "./Icon.css";
 
 const ICONS = {
   "arrow-right": {
diff --git a/client/components/ModuleItem.jsx b/client/components/ModuleItem.jsx
index 9bf4e884..93b13f58 100644
--- a/client/components/ModuleItem.jsx
+++ b/client/components/ModuleItem.jsx
@@ -1,10 +1,10 @@
+import cls from "classnames";
 import escapeRegExp from "escape-string-regexp";
-import { escape } from "html-escaper";
 import { filesize } from "filesize";
-import cls from "classnames";
+import { escape } from "html-escaper";
+import PureComponent from "../lib/PureComponent.jsx";
 
-import PureComponent from "../lib/PureComponent";
-import * as s from "./ModuleItem.css";
+import * as styles from "./ModuleItem.css";
 
 export default class ModuleItem extends PureComponent {
   state = {
@@ -13,8 +13,8 @@ export default class ModuleItem extends PureComponent {
 
   render({ module, showSize }) {
     const invisible = !this.state.visible;
-    const classes = cls(s.container, s[this.itemType], {
-      [s.invisible]: invisible,
+    const classes = cls(styles.container, styles[this.itemType], {
+      [styles.invisible]: invisible,
     });
 
     return (
@@ -57,10 +57,11 @@ export default class ModuleItem extends PureComponent {
       } while (match);
 
       if (lastMatch) {
-        html =
-          escape(title.slice(0, lastMatch.index)) +
-          `<strong>${escape(lastMatch[0])}</strong>` +
-          escape(title.slice(lastMatch.index + lastMatch[0].length));
+        html = `${escape(
+          title.slice(0, lastMatch.index),
+        )}<strong>${escape(lastMatch[0])}</strong>${escape(
+          title.slice(lastMatch.index + lastMatch[0].length),
+        )}`;
       }
     }
 
diff --git a/client/components/ModulesList.jsx b/client/components/ModulesList.jsx
index ee5c2098..50b605a6 100644
--- a/client/components/ModulesList.jsx
+++ b/client/components/ModulesList.jsx
@@ -1,12 +1,13 @@
 import cls from "classnames";
-import * as s from "./ModulesList.css";
-import ModuleItem from "./ModuleItem";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+import ModuleItem from "./ModuleItem.jsx";
+
+import * as styles from "./ModulesList.css";
 
 export default class ModulesList extends PureComponent {
   render({ modules, showSize, highlightedText, isModuleVisible, className }) {
     return (
-      <div className={cls(s.container, className)}>
+      <div className={cls(styles.container, className)}>
         {modules.map((module) => (
           <ModuleItem
             key={module.cid}
diff --git a/client/components/ModulesTreemap.jsx b/client/components/ModulesTreemap.jsx
index eeb0f10c..3ce96bc4 100644
--- a/client/components/ModulesTreemap.jsx
+++ b/client/components/ModulesTreemap.jsx
@@ -1,23 +1,23 @@
-import { Component } from "preact";
 import { filesize } from "filesize";
 import { computed, makeObservable } from "mobx";
 import { observer } from "mobx-react";
+import { Component } from "preact";
 
-import { isChunkParsed } from "../utils";
-import localStorage from "../localStorage";
-import Treemap from "./Treemap";
-import Tooltip from "./Tooltip";
-import Switcher from "./Switcher";
-import Sidebar from "./Sidebar";
-import Checkbox from "./Checkbox";
-import CheckboxList from "./CheckboxList";
-import ContextMenu from "./ContextMenu";
-
-import * as s from "./ModulesTreemap.css";
-import Search from "./Search";
-import { store } from "../store";
-import ModulesList from "./ModulesList";
-import Dropdown from "./Dropdown";
+import localStorage from "../localStorage.js";
+import { store } from "../store.js";
+import { isChunkParsed } from "../utils.js";
+import Checkbox from "./Checkbox.jsx";
+import CheckboxList from "./CheckboxList.jsx";
+import ContextMenu from "./ContextMenu.jsx";
+import Dropdown from "./Dropdown.jsx";
+import ModulesList from "./ModulesList.jsx";
+import Search from "./Search.jsx";
+import Sidebar from "./Sidebar.jsx";
+import Switcher from "./Switcher.jsx";
+import Tooltip from "./Tooltip.jsx";
+import Treemap from "./Treemap.jsx";
+
+import * as styles from "./ModulesTreemap.css";
 
 function getSizeSwitchItems() {
   const items = [
@@ -25,14 +25,17 @@ function getSizeSwitchItems() {
     { label: "Parsed", prop: "parsedSize" },
   ];
 
-  if (window.compressionAlgorithm === "gzip")
+  if (window.compressionAlgorithm === "gzip") {
     items.push({ label: "Gzipped", prop: "gzipSize" });
+  }
 
-  if (window.compressionAlgorithm === "brotli")
+  if (window.compressionAlgorithm === "brotli") {
     items.push({ label: "Brotli", prop: "brotliSize" });
+  }
 
-  if (window.compressionAlgorithm === "zstd")
+  if (window.compressionAlgorithm === "zstd") {
     items.push({ label: "Zstandard", prop: "zstdSize" });
+  }
 
   return items;
 }
@@ -83,14 +86,14 @@ class ModulesTreemap extends Component {
     } = this.state;
 
     return (
-      <div className={s.container}>
+      <div className={styles.container}>
         <Sidebar
           pinned={sidebarPinned}
           onToggle={this.handleSidebarToggle}
           onPinStateChange={this.handleSidebarPinStateChange}
           onResize={this.handleSidebarResize}
         >
-          <div className={s.sidebarGroup}>
+          <div className={styles.sidebarGroup}>
             <Switcher
               label="Treemap sizes"
               items={this.sizeSwitchItems}
@@ -98,7 +101,7 @@ class ModulesTreemap extends Component {
               onSwitch={this.handleSizeSwitch}
             />
             {store.hasConcatenatedModules && (
-              <div className={s.showOption}>
+              <div className={styles.showOption}>
                 <Checkbox
                   checked={store.showConcatenatedModulesContent}
                   onChange={this.handleConcatenatedModulesContentToggle}
@@ -108,33 +111,35 @@ class ModulesTreemap extends Component {
               </div>
             )}
           </div>
-          <div className={s.sidebarGroup}>
+          <div className={styles.sidebarGroup}>
             <Dropdown
               label="Filter to initial chunks"
               options={store.entrypoints}
               onSelectionChange={this.handleSelectionChange}
             />
           </div>
-          <div className={s.sidebarGroup}>
+          <div className={styles.sidebarGroup}>
             <Search
               label="Search modules"
               query={store.searchQuery}
               autofocus
               onQueryChange={this.handleQueryChange}
             />
-            <div className={s.foundModulesInfo}>{this.foundModulesInfo}</div>
+            <div className={styles.foundModulesInfo}>
+              {this.foundModulesInfo}
+            </div>
             {store.isSearching && store.hasFoundModules && (
-              <div className={s.foundModulesContainer}>
+              <div className={styles.foundModulesContainer}>
                 {store.foundModulesByChunk.map(({ chunk, modules }) => (
-                  <div key={chunk.cid} className={s.foundModulesChunk}>
+                  <div key={chunk.cid} className={styles.foundModulesChunk}>
                     <div
-                      className={s.foundModulesChunkName}
+                      className={styles.foundModulesChunkName}
                       onClick={() => this.treemap.zoomToGroup(chunk)}
                     >
                       {chunk.label}
                     </div>
                     <ModulesList
-                      className={s.foundModulesList}
+                      className={styles.foundModulesList}
                       modules={modules}
                       showSize={store.activeSize}
                       highlightedText={store.searchQueryRegexp}
@@ -147,7 +152,7 @@ class ModulesTreemap extends Component {
             )}
           </div>
           {this.chunkItems.length > 1 && (
-            <div className={s.sidebarGroup}>
+            <div className={styles.sidebarGroup}>
               <CheckboxList
                 label="Show chunks"
                 items={this.chunkItems}
@@ -160,7 +165,7 @@ class ModulesTreemap extends Component {
         </Sidebar>
         <Treemap
           ref={this.saveTreemapRef}
-          className={s.map}
+          className={styles.map}
           data={store.visibleChunks}
           highlightGroups={this.highlightedModules}
           weightProp={store.activeSize}
@@ -189,7 +194,7 @@ class ModulesTreemap extends Component {
     const isActive = store.activeSize === sizeProp;
 
     return typeof size === "number" ? (
-      <div className={isActive ? s.activeSize : ""}>
+      <div className={isActive ? styles.activeSize : ""}>
         {sizeLabel} size: <strong>{filesize(size)}</strong>
       </div>
     ) : null;
@@ -240,18 +245,16 @@ class ModulesTreemap extends Component {
 
     if (store.hasFoundModules) {
       return [
-        <div className={s.foundModulesInfoItem}>
+        <div className={styles.foundModulesInfoItem}>
           Count: <strong>{store.foundModules.length}</strong>
         </div>,
-        <div className={s.foundModulesInfoItem}>
+        <div className={styles.foundModulesInfoItem}>
           Total size: <strong>{filesize(store.foundModulesSize)}</strong>
         </div>,
       ];
-    } else {
-      return (
-        "Nothing found" + (store.allChunksSelected ? "" : " in selected chunks")
-      );
     }
+
+    return `Nothing found${store.allChunksSelected ? "" : " in selected chunks"}`;
   }
 
   handleSelectionChange = (selected) => {
diff --git a/client/components/Search.jsx b/client/components/Search.jsx
index d05a5bb9..ff207b7b 100644
--- a/client/components/Search.jsx
+++ b/client/components/Search.jsx
@@ -1,9 +1,10 @@
 // TODO: switch to a more modern debounce package once we drop Node.js 10 support
 import debounce from "debounce";
 
-import * as s from "./Search.css";
-import Button from "./Button";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+import Button from "./Button.jsx";
+
+import * as styles from "./Search.css";
 
 export default class Search extends PureComponent {
   componentDidMount() {
@@ -20,12 +21,12 @@ export default class Search extends PureComponent {
     const { label, query } = this.props;
 
     return (
-      <div className={s.container}>
-        <div className={s.label}>{label}:</div>
-        <div className={s.row}>
+      <div className={styles.container}>
+        <div className={styles.label}>{label}:</div>
+        <div className={styles.row}>
           <input
             ref={this.saveInputNode}
-            className={s.input}
+            className={styles.input}
             type="text"
             value={query}
             placeholder="Enter regexp"
@@ -33,7 +34,7 @@ export default class Search extends PureComponent {
             onBlur={this.handleInputBlur}
             onKeyDown={this.handleKeyDown}
           />
-          <Button className={s.clear} onClick={this.handleClearClick}>
+          <Button className={styles.clear} onClick={this.handleClearClick}>
             x
           </Button>
         </div>
diff --git a/client/components/Sidebar.jsx b/client/components/Sidebar.jsx
index 54f668c5..0467d97e 100644
--- a/client/components/Sidebar.jsx
+++ b/client/components/Sidebar.jsx
@@ -1,12 +1,13 @@
-import { Component } from "preact";
 import cls from "classnames";
+import { Component } from "preact";
 
-import * as s from "./Sidebar.css";
-import Button from "./Button";
-import Icon from "./Icon";
-import ThemeToggle from "./ThemeToggle";
+import Button from "./Button.jsx";
+import Icon from "./Icon.jsx";
+import ThemeToggle from "./ThemeToggle.jsx";
 
-const toggleTime = parseInt(s.toggleTime);
+import * as styles from "./Sidebar.css";
+
+const toggleTime = parseInt(styles.toggleTime, 10);
 
 export default class Sidebar extends Component {
   static defaultProps = {
@@ -15,9 +16,13 @@ export default class Sidebar extends Component {
   };
 
   allowHide = true;
+
   toggling = false;
+
   hideContentTimeout = null;
+
   width = null;
+
   state = {
     visible: true,
     renderContent: true,
@@ -37,11 +42,11 @@ export default class Sidebar extends Component {
     const { visible, renderContent } = this.state;
 
     const className = cls({
-      [s.container]: true,
-      [s.pinned]: pinned,
-      [s.left]: position === "left",
-      [s.hidden]: !visible,
-      [s.empty]: !renderContent,
+      [styles.container]: true,
+      [styles.pinned]: pinned,
+      [styles.left]: position === "left",
+      [styles.hidden]: !visible,
+      [styles.empty]: !renderContent,
     });
 
     return (
@@ -56,7 +61,7 @@ export default class Sidebar extends Component {
           <Button
             type="button"
             title="Pin"
-            className={s.pinButton}
+            className={styles.pinButton}
             active={pinned}
             toggle
             onClick={this.handlePinButtonClick}
@@ -67,16 +72,19 @@ export default class Sidebar extends Component {
         <Button
           type="button"
           title={visible ? "Hide" : "Show sidebar"}
-          className={s.toggleButton}
+          className={styles.toggleButton}
           onClick={this.handleToggleButtonClick}
         >
           <Icon name="arrow-right" size={10} rotate={visible ? 180 : 0} />
         </Button>
         {pinned && visible && (
-          <div className={s.resizer} onMouseDown={this.handleResizeStart} />
+          <div
+            className={styles.resizer}
+            onMouseDown={this.handleResizeStart}
+          />
         )}
         <div
-          className={s.content}
+          className={styles.content}
           onMouseEnter={this.handleMouseEnter}
           onMouseMove={this.handleMouseMove}
         >
diff --git a/client/components/Switcher.jsx b/client/components/Switcher.jsx
index d9f7ef7f..3ad03784 100644
--- a/client/components/Switcher.jsx
+++ b/client/components/Switcher.jsx
@@ -1,19 +1,20 @@
-import SwitcherItem from "./SwitcherItem";
-import * as s from "./Switcher.css";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+import SwitcherItem from "./SwitcherItem.jsx";
+
+import * as styles from "./Switcher.css";
 
 export default class Switcher extends PureComponent {
   render() {
     const { label, items, activeItem, onSwitch } = this.props;
 
     return (
-      <div className={s.container}>
-        <div className={s.label}>{label}:</div>
+      <div className={styles.container}>
+        <div className={styles.label}>{label}:</div>
         <div>
           {items.map((item) => (
             <SwitcherItem
               key={item.label}
-              className={s.item}
+              className={styles.item}
               item={item}
               active={item === activeItem}
               onClick={onSwitch}
diff --git a/client/components/SwitcherItem.jsx b/client/components/SwitcherItem.jsx
index fd672f90..8f32c704 100644
--- a/client/components/SwitcherItem.jsx
+++ b/client/components/SwitcherItem.jsx
@@ -1,5 +1,5 @@
-import Button from "./Button";
-import PureComponent from "../lib/PureComponent";
+import PureComponent from "../lib/PureComponent.jsx";
+import Button from "./Button.jsx";
 
 export default class SwitcherItem extends PureComponent {
   render({ item, ...props }) {
diff --git a/client/components/ThemeToggle.jsx b/client/components/ThemeToggle.jsx
index 072fde63..67d95032 100644
--- a/client/components/ThemeToggle.jsx
+++ b/client/components/ThemeToggle.jsx
@@ -1,10 +1,11 @@
-import { Component } from "preact";
 import { observer } from "mobx-react";
+import { Component } from "preact";
+
+import { store } from "../store.js";
+import Button from "./Button.jsx";
+import Icon from "./Icon.jsx";
 
-import * as s from "./ThemeToggle.css";
-import Button from "./Button";
-import Icon from "./Icon";
-import { store } from "../store";
+import * as styles from "./ThemeToggle.css";
 
 class ThemeToggle extends Component {
   render() {
@@ -14,7 +15,7 @@ class ThemeToggle extends Component {
       <Button
         type="button"
         title={darkMode ? "Switch to Light Mode" : "Switch to Dark Mode"}
-        className={s.themeToggle}
+        className={styles.themeToggle}
         onClick={this.handleToggle}
       >
         <Icon name={darkMode ? "sun" : "moon"} size={16} />
diff --git a/client/components/Tooltip.jsx b/client/components/Tooltip.jsx
index cd5b4caf..e8af8f81 100644
--- a/client/components/Tooltip.jsx
+++ b/client/components/Tooltip.jsx
@@ -1,10 +1,11 @@
-import { Component } from "preact";
 import cls from "classnames";
+import { Component } from "preact";
 
-import * as s from "./Tooltip.css";
+import * as styles from "./Tooltip.css";
 
 export default class Tooltip extends Component {
   static marginX = 10;
+
   static marginY = 30;
 
   mouseCoords = {
@@ -32,8 +33,8 @@ export default class Tooltip extends Component {
   render() {
     const { children, visible } = this.props;
     const className = cls({
-      [s.container]: true,
-      [s.hidden]: !visible,
+      [styles.container]: true,
+      [styles.hidden]: !visible,
     });
 
     return (
diff --git a/client/components/Treemap.jsx b/client/components/Treemap.jsx
index 1b1aabd1..89985cac 100644
--- a/client/components/Treemap.jsx
+++ b/client/components/Treemap.jsx
@@ -1,5 +1,5 @@
-import { Component } from "preact";
 import FoamTree from "@carrotsearch/foamtree";
+import { Component } from "preact";
 
 export default class Treemap extends Component {
   constructor(props) {
@@ -75,7 +75,7 @@ export default class Treemap extends Component {
         const chunkName = component.getChunkNamePart(root.label);
         const hash = /[^0-9]/u.test(chunkName)
           ? hashCode(chunkName)
-          : (parseInt(chunkName) / 1000) * 360;
+          : (Number.parseInt(chunkName) / 1000) * 360;
         variables.groupColor = {
           model: "hsla",
           h: Math.round(Math.abs(hash) % 360),
@@ -177,7 +177,7 @@ export default class Treemap extends Component {
 
   isGroupRendered(group) {
     const groupState = this.treemap.get("state", group);
-    return !!groupState && groupState.revealed;
+    return Boolean(groupState) && groupState.revealed;
   }
 
   update() {
@@ -256,7 +256,7 @@ function hashCode(str) {
   for (let i = 0; i < str.length; i++) {
     const code = str.charCodeAt(i);
     hash = (hash << 5) - hash + code;
-    hash = hash & hash;
+    hash &= hash;
   }
   return hash;
 }
diff --git a/client/localStorage.js b/client/localStorage.js
index 44e093b4..fca600c3 100644
--- a/client/localStorage.js
+++ b/client/localStorage.js
@@ -4,7 +4,7 @@ export default {
   getItem(key) {
     try {
       return JSON.parse(window.localStorage.getItem(`${KEY_PREFIX}.${key}`));
-    } catch (err) {
+    } catch {
       return null;
     }
   },
@@ -15,7 +15,7 @@ export default {
         `${KEY_PREFIX}.${key}`,
         JSON.stringify(value),
       );
-    } catch (err) {
+    } catch {
       /* ignored */
     }
   },
@@ -23,7 +23,7 @@ export default {
   removeItem(key) {
     try {
       window.localStorage.removeItem(`${KEY_PREFIX}.${key}`);
-    } catch (err) {
+    } catch {
       /* ignored */
     }
   },
diff --git a/client/store.js b/client/store.js
index b309ac3c..79bc8a54 100644
--- a/client/store.js
+++ b/client/store.js
@@ -1,9 +1,10 @@
-import { observable, computed, makeObservable } from "mobx";
-import { isChunkParsed, walkModules } from "./utils";
+import { computed, makeObservable, observable } from "mobx";
 import localStorage from "./localStorage";
+import { isChunkParsed, walkModules } from "./utils";
 
 export class Store {
   cid = 0;
+
   sizes = new Set([
     "statSize",
     "parsedSize",
@@ -13,12 +14,18 @@ export class Store {
   ]);
 
   allChunks;
+
   selectedChunks;
+
   searchQuery = "";
+
   defaultSize;
+
   selectedSize;
+
   showConcatenatedModulesContent =
     localStorage.getItem("showConcatenatedModulesContent") === true;
+
   darkMode = (() => {
     const systemPrefersDark = window.matchMedia(
       "(prefers-color-scheme: dark)",
@@ -27,7 +34,7 @@ export class Store {
     try {
       const saved = localStorage.getItem("darkMode");
       if (saved !== null) return saved === "true";
-    } catch (e) {
+    } catch {
       // Some browsers might not have localStorage available and we can fail silently
     }
 
@@ -114,7 +121,7 @@ export class Store {
 
     try {
       return new RegExp(query, "iu");
-    } catch (err) {
+    } catch {
       return null;
     }
   }
@@ -167,13 +174,13 @@ export class Store {
         // Filtering out missing groups
         foundGroups = foundGroups.filter(Boolean).reverse();
         // Sorting each group by active size
-        foundGroups.forEach((modules) =>
-          modules.sort((m1, m2) => m2[activeSize] - m1[activeSize]),
-        );
+        for (const modules of foundGroups) {
+          modules.sort((m1, m2) => m2[activeSize] - m1[activeSize]);
+        }
 
         return {
           chunk,
-          modules: [].concat(...foundGroups),
+          modules: foundGroups.flat(),
         };
       })
       .filter((result) => result.modules.length > 0)
@@ -238,7 +245,7 @@ export class Store {
     this.darkMode = !this.darkMode;
     try {
       localStorage.setItem("darkMode", this.darkMode);
-    } catch (e) {
+    } catch {
       // Some browsers might not have localStorage available and we can fail silently
     }
     this.updateTheme();
diff --git a/client/utils.js b/client/utils.js
index 41e2646c..6e99cd40 100644
--- a/client/utils.js
+++ b/client/utils.js
@@ -6,10 +6,8 @@ export function walkModules(modules, cb) {
   for (const module of modules) {
     if (cb(module) === false) return false;
 
-    if (module.groups) {
-      if (walkModules(module.groups, cb) === false) {
-        return false;
-      }
+    if (module.groups && walkModules(module.groups, cb) === false) {
+      return false;
     }
   }
 }
diff --git a/client/viewer.jsx b/client/viewer.jsx
index 58b22c12..185db8f4 100644
--- a/client/viewer.jsx
+++ b/client/viewer.jsx
@@ -1,7 +1,8 @@
 import { render } from "preact";
 
-import { store } from "./store";
-import ModulesTreemap from "./components/ModulesTreemap";
+import ModulesTreemap from "./components/ModulesTreemap.jsx";
+import { store } from "./store.js";
+
 import "./viewer.css";
 
 // Initializing WebSocket for live treemap updates
@@ -10,7 +11,7 @@ try {
   if (window.enableWebSocket) {
     ws = new WebSocket(`ws://${location.host}`);
   }
-} catch (err) {
+} catch {
   console.warn(
     "Couldn't connect to analyzer websocket server so you'll have to reload page manually to see updates in the treemap",
   );
diff --git a/jest.config.js b/jest.config.js
index 85f6834f..492febad 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,3 +1,5 @@
+"use strict";
+
 // Jest configuration
 // Reference: https://jestjs.io/docs/configuration
 
diff --git a/src/BundleAnalyzerPlugin.js b/src/BundleAnalyzerPlugin.js
index 6f48a9f0..65287b4f 100644
--- a/src/BundleAnalyzerPlugin.js
+++ b/src/BundleAnalyzerPlugin.js
@@ -1,11 +1,11 @@
-const fs = require("fs");
-const path = require("path");
+const fs = require("node:fs");
+const path = require("node:path");
 const { bold } = require("picocolors");
 
 const Logger = require("./Logger");
-const viewer = require("./viewer");
-const utils = require("./utils");
 const { writeStats } = require("./statsUtils");
+const utils = require("./utils");
+const viewer = require("./viewer");
 
 class BundleAnalyzerPlugin {
   constructor(opts = {}) {
@@ -42,7 +42,7 @@ class BundleAnalyzerPlugin {
     this.compiler = compiler;
 
     const done = (stats, callback) => {
-      callback = callback || (() => {});
+      callback ||= () => {};
 
       const actions = [];
 
@@ -71,8 +71,8 @@ class BundleAnalyzerPlugin {
           try {
             await Promise.all(actions.map((action) => action()));
             callback();
-          } catch (e) {
-            callback(e);
+          } catch (err) {
+            callback(err);
           }
         });
       } else {
diff --git a/src/Logger.js b/src/Logger.js
index cd62385a..68584529 100644
--- a/src/Logger.js
+++ b/src/Logger.js
@@ -8,6 +8,7 @@ const LEVEL_TO_CONSOLE_METHOD = new Map([
 
 class Logger {
   static levels = LEVELS;
+
   static defaultLevel = "info";
 
   constructor(level = Logger.defaultLevel) {
@@ -18,10 +19,11 @@ class Logger {
   setLogLevel(level) {
     const levelIndex = LEVELS.indexOf(level);
 
-    if (levelIndex === -1)
+    if (levelIndex === -1) {
       throw new Error(
         `Invalid log level "${level}". Use one of these: ${LEVELS.join(", ")}`,
       );
+    }
 
     this.activeLevels.clear();
 
@@ -35,12 +37,12 @@ class Logger {
   }
 }
 
-LEVELS.forEach((level) => {
-  if (level === "silent") return;
+for (const level of LEVELS) {
+  if (level === "silent") continue;
 
-  Logger.prototype[level] = function (...args) {
+  Logger.prototype[level] = function log(...args) {
     if (this.activeLevels.has(level)) this._log(level, ...args);
   };
-});
+}
 
 module.exports = Logger;
diff --git a/src/analyzer.js b/src/analyzer.js
index 6f59b4cd..8a1ad656 100644
--- a/src/analyzer.js
+++ b/src/analyzer.js
@@ -1,13 +1,13 @@
-const fs = require("fs");
-const path = require("path");
+const fs = require("node:fs");
+const path = require("node:path");
 
 const { parseChunked } = require("@discoveryjs/json-ext");
 
 const Logger = require("./Logger");
-const Folder = require("./tree/Folder").default;
 const { parseBundle } = require("./parseUtils");
-const { createAssetsFilter } = require("./utils");
 const { getCompressedSize } = require("./sizeUtils");
+const Folder = require("./tree/Folder").default;
+const { createAssetsFilter } = require("./utils");
 
 const FILENAME_QUERY_REGEXP = /\?.*$/u;
 const FILENAME_EXTENSIONS = /\.(js|mjs|cjs|bundle)$/iu;
@@ -28,7 +28,9 @@ function getViewerData(bundleStats, bundleDir, opts) {
 
   // Sometimes all the information is located in `children` array (e.g. problem in #10)
   if (
-    (bundleStats.assets == null || bundleStats.assets.length === 0) &&
+    (bundleStats.assets === null ||
+      bundleStats.assets === undefined ||
+      bundleStats.assets.length === 0) &&
     bundleStats.children &&
     bundleStats.children.length > 0
   ) {
@@ -37,19 +39,19 @@ function getViewerData(bundleStats, bundleDir, opts) {
     // Sometimes if there are additional child chunks produced add them as child assets,
     // leave the 1st one as that is considered the 'root' asset.
     for (let i = 1; i < children.length; i++) {
-      children[i].assets.forEach((asset) => {
+      for (const asset of children[i].assets) {
         asset.isChild = true;
         bundleStats.assets.push(asset);
-      });
+      }
     }
   } else if (bundleStats.children && bundleStats.children.length > 0) {
     // Sometimes if there are additional child chunks produced add them as child assets
-    bundleStats.children.forEach((child) => {
-      child.assets.forEach((asset) => {
+    for (const child of bundleStats.children) {
+      for (const asset of child.assets) {
         asset.isChild = true;
         bundleStats.assets.push(asset);
-      });
-    });
+      }
+    }
   }
 
   // Picking only `*.js, *.cjs or *.mjs` assets from bundle that has non-empty `chunks` array
@@ -120,19 +122,21 @@ function getViewerData(bundleStats, bundleDir, opts) {
       size: statAsset.size,
     });
     const assetSources =
-      bundlesSources &&
-      Object.prototype.hasOwnProperty.call(bundlesSources, statAsset.name)
+      bundlesSources && Object.hasOwn(bundlesSources, statAsset.name)
         ? bundlesSources[statAsset.name]
         : null;
 
     if (assetSources) {
       asset.parsedSize = Buffer.byteLength(assetSources.src);
-      if (compressionAlgorithm === "gzip")
+      if (compressionAlgorithm === "gzip") {
         asset.gzipSize = getCompressedSize("gzip", assetSources.src);
-      if (compressionAlgorithm === "brotli")
+      }
+      if (compressionAlgorithm === "brotli") {
         asset.brotliSize = getCompressedSize("brotli", assetSources.src);
-      if (compressionAlgorithm === "zstd")
+      }
+      if (compressionAlgorithm === "zstd") {
         asset.zstdSize = getCompressedSize("zstd", assetSources.src);
+      }
     }
 
     // Picking modules from current bundle script
@@ -208,8 +212,8 @@ function readStatsFromFile(filename) {
 
 function getChildAssetBundles(bundleStats, assetName) {
   return flatten(
-    (bundleStats.children || []).find((c) =>
-      Object.values(c.assetsByChunkName),
+    (bundleStats.children || []).find((child) =>
+      Object.values(child.assetsByChunkName),
     ),
   ).includes(assetName);
 }
@@ -252,14 +256,17 @@ function isRuntimeModule(statModule) {
 function createModulesTree(modules, opts) {
   const root = new Folder(".", opts);
 
-  modules.forEach((module) => root.addModule(module));
+  for (const module of modules) {
+    root.addModule(module);
+  }
+
   root.mergeNestedFolders();
 
   return root;
 }
 
 function getChunkToInitialByEntrypoint(bundleStats) {
-  if (bundleStats == null) {
+  if (bundleStats === null || bundleStats === undefined) {
     return {};
   }
   const chunkToEntrypointInititalMap = {};
diff --git a/src/bin/analyzer.js b/src/bin/analyzer.js
index afe4f052..135c109c 100755
--- a/src/bin/analyzer.js
+++ b/src/bin/analyzer.js
@@ -1,15 +1,15 @@
 #! /usr/bin/env node
 
-const { resolve, dirname } = require("path");
+const { dirname, resolve } = require("node:path");
 
 const { program: commanderProgram } = require("commander");
 const { magenta } = require("picocolors");
 
-const analyzer = require("../analyzer");
-const viewer = require("../viewer");
 const Logger = require("../Logger");
-const utils = require("../utils");
+const analyzer = require("../analyzer");
 const { isZstdSupported } = require("../sizeUtils");
+const utils = require("../utils");
+const viewer = require("../viewer");
 
 const SIZES = new Set(["stat", "parsed", "gzip"]);
 const COMPRESSION_ALGORITHMS = new Set(
@@ -26,16 +26,13 @@ const program = commanderProgram
   )
   .option(
     "-m, --mode <mode>",
-    "Analyzer mode. Should be `server`,`static` or `json`." +
-      br(
-        "In `server` mode analyzer will start HTTP server to show bundle report.",
-      ) +
-      br(
-        "In `static` mode single HTML file with bundle report will be generated.",
-      ) +
-      br(
-        "In `json` mode single JSON file with bundle report will be generated.",
-      ),
+    `Analyzer mode. Should be \`server\`,\`static\` or \`json\`.${br(
+      "In `server` mode analyzer will start HTTP server to show bundle report.",
+    )}${br(
+      "In `static` mode single HTML file with bundle report will be generated.",
+    )}${br(
+      "In `json` mode single JSON file with bundle report will be generated.",
+    )}`,
     "server",
   )
   .option(
@@ -60,14 +57,16 @@ const program = commanderProgram
   )
   .option(
     "-s, --default-sizes <type>",
-    "Module sizes to show in treemap by default." +
-      br(`Possible values: ${[...SIZES].join(", ")}`),
+    `Module sizes to show in treemap by default.${br(
+      `Possible values: ${[...SIZES].join(", ")}`,
+    )}`,
     "parsed",
   )
   .option(
     "--compression-algorithm <type>",
-    "Compression algorithm that will be used to calculate the compressed module sizes." +
-      br(`Possible values: ${[...COMPRESSION_ALGORITHMS].join(", ")}`),
+    `Compression algorithm that will be used to calculate the compressed module sizes.${br(
+      `Possible values: ${[...COMPRESSION_ALGORITHMS].join(", ")}`,
+    )}`,
     "gzip",
   )
   .option(
@@ -76,13 +75,14 @@ const program = commanderProgram
   )
   .option(
     "-e, --exclude <regexp>",
-    "Assets that should be excluded from the report." +
-      br("Can be specified multiple times."),
+    `Assets that should be excluded from the report.${br(
+      "Can be specified multiple times.",
+    )}`,
     array(),
   )
   .option(
     "-l, --log-level <level>",
-    "Log level." + br(`Possible values: ${[...Logger.levels].join(", ")}`),
+    `Log level.${br(`Possible values: ${[...Logger.levels].join(", ")}`)}`,
     Logger.defaultLevel,
   )
   .parse();
@@ -106,8 +106,9 @@ if (typeof reportTitle === "undefined") {
   reportTitle = utils.defaultTitle;
 }
 
-if (!bundleStatsFile)
+if (!bundleStatsFile) {
   showHelp("Provide path to Webpack Stats file as first argument");
+}
 if (mode !== "server" && mode !== "static" && mode !== "json") {
   showHelp("Invalid mode. Should be either `server`, `static` or `json`.");
 }
@@ -122,10 +123,11 @@ if (!COMPRESSION_ALGORITHMS.has(compressionAlgorithm)) {
     `Invalid compression algorithm option. Possible values are: ${[...COMPRESSION_ALGORITHMS].join(", ")}`,
   );
 }
-if (!SIZES.has(defaultSizes))
+if (!SIZES.has(defaultSizes)) {
   showHelp(
     `Invalid default sizes option. Possible values are: ${[...SIZES].join(", ")}`,
   );
+}
 
 bundleStatsFile = resolve(bundleStatsFile);
 
diff --git a/src/parseUtils.js b/src/parseUtils.js
index 2ace9d30..f4025f9c 100644
--- a/src/parseUtils.js
+++ b/src/parseUtils.js
@@ -1,12 +1,8 @@
-const fs = require("fs");
+const fs = require("node:fs");
 const acorn = require("acorn");
 const walk = require("acorn-walk");
 
-module.exports = {
-  parseBundle,
-};
-
-function parseBundle(bundlePath, opts) {
+module.exports.parseBundle = function parseBundle(bundlePath, opts) {
   const { sourceType = "script" } = opts || {};
 
   const content = fs.readFileSync(bundlePath, "utf8");
@@ -136,7 +132,9 @@ function parseBundle(bundlePath, opts) {
 
       // Walking into arguments because some of plugins (e.g. `DedupePlugin`) or some Webpack
       // features (e.g. `umd` library output) can wrap modules list into additional IIFE.
-      args.forEach((arg) => c(arg, state));
+      for (const arg of args) {
+        c(arg, state);
+      }
     },
   });
 
@@ -153,7 +151,7 @@ function parseBundle(bundlePath, opts) {
     src: content,
     runtimeSrc: getBundleRuntime(content, walkState.locations),
   };
-}
+};
 
 /**
  * Returns bundle source except modules
@@ -171,7 +169,7 @@ function getBundleRuntime(content, modulesLocations) {
     lastIndex = end;
   }
 
-  return result + content.slice(lastIndex, content.length);
+  return result + content.slice(lastIndex);
 }
 
 function isIIFE(node) {
@@ -186,9 +184,8 @@ function isIIFE(node) {
 function getIIFECallExpression(node) {
   if (node.expression.type === "UnaryExpression") {
     return node.expression.argument;
-  } else {
-    return node.expression;
   }
+  return node.expression;
 }
 
 function isModulesList(node) {
diff --git a/src/sizeUtils.js b/src/sizeUtils.js
index 2eb4ac8e..1919a244 100644
--- a/src/sizeUtils.js
+++ b/src/sizeUtils.js
@@ -1,4 +1,4 @@
-const zlib = require("zlib");
+const zlib = require("node:zlib");
 
 export const isZstdSupported = "createZstdCompress" in zlib;
 
diff --git a/src/statsUtils.js b/src/statsUtils.js
index 8a8c06e6..5bac3039 100644
--- a/src/statsUtils.js
+++ b/src/statsUtils.js
@@ -1,5 +1,5 @@
-const { createWriteStream } = require("fs");
-const { Readable } = require("stream");
+const { createWriteStream } = require("node:fs");
+const { Readable } = require("node:stream");
 
 class StatsSerializeStream extends Readable {
   constructor(stats) {
@@ -74,9 +74,6 @@ class StatsSerializeStream extends Readable {
   }
 }
 
-exports.StatsSerializeStream = StatsSerializeStream;
-exports.writeStats = writeStats;
-
 async function writeStats(stats, filepath) {
   return new Promise((resolve, reject) => {
     new StatsSerializeStream(stats)
@@ -85,3 +82,5 @@ async function writeStats(stats, filepath) {
       .pipe(createWriteStream(filepath));
   });
 }
+
+module.exports = { StatsSerializeStream, writeStats };
diff --git a/src/template.js b/src/template.js
index 55d1ab15..673d6531 100644
--- a/src/template.js
+++ b/src/template.js
@@ -1,19 +1,17 @@
 /* eslint-disable max-len */
-const path = require("path");
-const fs = require("fs");
+const fs = require("node:fs");
+const path = require("node:path");
 
 const { escape } = require("html-escaper");
 
 const projectRoot = path.resolve(__dirname, "..");
 const assetsRoot = path.join(projectRoot, "public");
 
-exports.renderViewer = renderViewer;
-
 /**
  * Escapes `<` characters in JSON to safely use it in `<script>` tag.
  */
 function escapeJson(json) {
-  return JSON.stringify(json).replace(/</gu, "\\u003c");
+  return JSON.stringify(json).replaceAll("<", "\\u003c");
 }
 
 function getAssetContent(filename) {
@@ -36,9 +34,9 @@ function getScript(filename, mode) {
   if (mode === "static") {
     return `<!-- ${escape(filename)} -->
 <script>${getAssetContent(filename)}</script>`;
-  } else {
-    return `<script src="${escape(filename)}"></script>`;
   }
+
+  return `<script src="${escape(filename)}"></script>`;
 }
 
 function renderViewer({
@@ -79,3 +77,5 @@ function renderViewer({
       </body>
     </html>`;
 }
+
+module.exports = { renderViewer };
diff --git a/src/tree/BaseFolder.js b/src/tree/BaseFolder.js
index 1cdbef94..55603e20 100644
--- a/src/tree/BaseFolder.js
+++ b/src/tree/BaseFolder.js
@@ -7,7 +7,7 @@ export default class BaseFolder extends Node {
   }
 
   get src() {
-    if (!Object.prototype.hasOwnProperty.call(this, "_src")) {
+    if (!Object.hasOwn(this, "_src")) {
       this._src = this.walk((node, src) => (src += node.src || ""), "", false);
     }
 
@@ -15,7 +15,7 @@ export default class BaseFolder extends Node {
   }
 
   get size() {
-    if (!Object.prototype.hasOwnProperty.call(this, "_size")) {
+    if (!Object.hasOwn(this, "_size")) {
       this._size = this.walk((node, size) => size + node.size, 0, false);
     }
 
@@ -59,22 +59,21 @@ export default class BaseFolder extends Node {
   walk(walker, state = {}, deep = true) {
     let stopped = false;
 
+    function stop(finalState) {
+      stopped = true;
+      return finalState;
+    }
+
     Object.values(this.children).forEach((child) => {
-      if (deep && child.walk) {
-        state = child.walk(walker, state, stop);
-      } else {
-        state = walker(child, state, stop);
-      }
+      state =
+        deep && child.walk
+          ? child.walk(walker, state, stop)
+          : walker(child, state, stop);
 
       if (stopped) return false;
     });
 
     return state;
-
-    function stop(finalState) {
-      stopped = true;
-      return finalState;
-    }
   }
 
   mergeNestedFolders() {
@@ -82,7 +81,7 @@ export default class BaseFolder extends Node {
       let childNames;
 
       while ((childNames = Object.keys(this.children)).length === 1) {
-        const childName = childNames[0];
+        const [childName] = childNames;
         const onlyChild = this.children[childName];
 
         if (onlyChild instanceof this.constructor) {
diff --git a/src/tree/ConcatenatedModule.js b/src/tree/ConcatenatedModule.js
index d9e25ea0..57b8daf2 100644
--- a/src/tree/ConcatenatedModule.js
+++ b/src/tree/ConcatenatedModule.js
@@ -1,6 +1,6 @@
-import Module from "./Module";
-import ContentModule from "./ContentModule";
 import ContentFolder from "./ContentFolder";
+import ContentModule from "./ContentModule";
+import Module from "./Module";
 import { getModulePathParts } from "./utils";
 
 export default class ConcatenatedModule extends Module {
@@ -36,9 +36,9 @@ export default class ConcatenatedModule extends Module {
   }
 
   fillContentModules() {
-    this.data.modules.forEach((moduleData) =>
-      this.addContentModule(moduleData),
-    );
+    for (const moduleData of this.data.modules) {
+      this.addContentModule(moduleData);
+    }
   }
 
   addContentModule(moduleData) {
@@ -54,7 +54,7 @@ export default class ConcatenatedModule extends Module {
     ];
     let currentFolder = this;
 
-    folders.forEach((folderName) => {
+    for (const folderName of folders) {
       let childFolder = currentFolder.getChild(folderName);
 
       if (!childFolder) {
@@ -64,7 +64,7 @@ export default class ConcatenatedModule extends Module {
       }
 
       currentFolder = childFolder;
-    });
+    }
 
     const ModuleConstructor = moduleData.modules
       ? ConcatenatedModule
diff --git a/src/tree/Folder.js b/src/tree/Folder.js
index 704c2113..452a928b 100644
--- a/src/tree/Folder.js
+++ b/src/tree/Folder.js
@@ -1,8 +1,8 @@
-import Module from "./Module";
+import { getCompressedSize } from "../sizeUtils";
 import BaseFolder from "./BaseFolder";
 import ConcatenatedModule from "./ConcatenatedModule";
+import Module from "./Module";
 import { getModulePathParts } from "./utils";
-import { getCompressedSize } from "../sizeUtils";
 
 export default class Folder extends BaseFolder {
   constructor(name, opts) {
@@ -35,7 +35,7 @@ export default class Folder extends BaseFolder {
   getCompressedSize(compressionAlgorithm) {
     const key = `_${compressionAlgorithm}Size`;
 
-    if (!Object.prototype.hasOwnProperty.call(this, key)) {
+    if (!Object.hasOwn(this, key)) {
       this[key] = this.src
         ? getCompressedSize(compressionAlgorithm, this.src)
         : 0;
@@ -57,7 +57,7 @@ export default class Folder extends BaseFolder {
     ];
     let currentFolder = this;
 
-    folders.forEach((folderName) => {
+    for (const folderName of folders) {
       let childNode = currentFolder.getChild(folderName);
 
       if (
@@ -75,7 +75,7 @@ export default class Folder extends BaseFolder {
       }
 
       currentFolder = childNode;
-    });
+    }
 
     const ModuleConstructor = moduleData.modules ? ConcatenatedModule : Module;
     const module = new ModuleConstructor(fileName, moduleData, this, this.opts);
diff --git a/src/tree/Module.js b/src/tree/Module.js
index 4c52c56f..e126d63b 100644
--- a/src/tree/Module.js
+++ b/src/tree/Module.js
@@ -1,5 +1,5 @@
-import Node from "./Node";
 import { getCompressedSize } from "../sizeUtils";
+import Node from "./Node";
 
 export default class Module extends Node {
   constructor(name, data, parent, opts) {
diff --git a/src/utils.js b/src/utils.js
index ae59d2fc..2cb94f8a 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -1,4 +1,4 @@
-const { inspect, types } = require("util");
+const { inspect, types } = require("node:util");
 const opener = require("opener");
 
 const MONTHS = [
@@ -16,8 +16,6 @@ const MONTHS = [
   "Dec",
 ];
 
-exports.createAssetsFilter = createAssetsFilter;
-
 function createAssetsFilter(excludePatterns) {
   const excludeFunctions = (
     Array.isArray(excludePatterns) ? excludePatterns : [excludePatterns]
@@ -43,16 +41,21 @@ function createAssetsFilter(excludePatterns) {
 
   if (excludeFunctions.length) {
     return (asset) => excludeFunctions.every((fn) => fn(asset) !== true);
-  } else {
-    return () => true;
   }
+
+  return () => true;
 }
 
 /**
  * @desc get string of current time
  * format: dd/MMM HH:mm
  * */
-exports.defaultTitle = function () {
+function defaultAnalyzerUrl(options) {
+  const { listenHost, boundAddress } = options;
+  return `http://${listenHost}:${boundAddress.port}`;
+}
+
+function defaultTitle() {
   const time = new Date();
   const year = time.getFullYear();
   const month = MONTHS[time.getMonth()];
@@ -63,20 +66,17 @@ exports.defaultTitle = function () {
   const currentTime = `${day} ${month} ${year} at ${hour}:${minute}`;
 
   return `${process.env.npm_package_name || "Webpack Bundle Analyzer"} [${currentTime}]`;
-};
-
-exports.defaultAnalyzerUrl = function (options) {
-  const { listenHost, boundAddress } = options;
-  return `http://${listenHost}:${boundAddress.port}`;
-};
+}
 
 /**
  * Calls opener on a URI, but silently try / catches it.
  */
-exports.open = function (uri, logger) {
+function open(uri, logger) {
   try {
     opener(uri);
   } catch (err) {
     logger.debug(`Opener failed to open "${uri}":\n${err}`);
   }
-};
+}
+
+module.exports = { createAssetsFilter, defaultAnalyzerUrl, defaultTitle, open };
diff --git a/src/viewer.js b/src/viewer.js
index 4808c345..fb7cd4e4 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -1,41 +1,34 @@
-const path = require("path");
-const fs = require("fs");
-const http = require("http");
+const fs = require("node:fs");
+const http = require("node:http");
+const path = require("node:path");
 
-const WebSocket = require("ws");
-const sirv = require("sirv");
 const { bold } = require("picocolors");
+const sirv = require("sirv");
+const WebSocket = require("ws");
 
 const Logger = require("./Logger");
 const analyzer = require("./analyzer");
-const { open } = require("./utils");
 const { renderViewer } = require("./template");
+const { open } = require("./utils");
 
 const projectRoot = path.resolve(__dirname, "..");
 
 function resolveTitle(reportTitle) {
   if (typeof reportTitle === "function") {
     return reportTitle();
-  } else {
-    return reportTitle;
   }
+
+  return reportTitle;
 }
 
 function resolveDefaultSizes(defaultSizes, compressionAlgorithm) {
-  if (["gzip", "brotli", "zstd"].includes(defaultSizes))
+  if (["gzip", "brotli", "zstd"].includes(defaultSizes)) {
     return compressionAlgorithm;
+  }
+
   return defaultSizes;
 }
 
-module.exports = {
-  startServer,
-  generateReport,
-  generateJSONReport,
-  getEntrypoints,
-  // deprecated
-  start: startServer,
-};
-
 async function startServer(bundleStats, opts) {
   const {
     port = 8888,
@@ -112,12 +105,6 @@ async function startServer(bundleStats, opts) {
     });
   });
 
-  return {
-    ws: wss,
-    http: server,
-    updateChartData,
-  };
-
   function updateChartData(bundleStats) {
     const newChartData = getChartData(analyzerOpts, bundleStats, bundleDir);
 
@@ -125,7 +112,7 @@ async function startServer(bundleStats, opts) {
 
     chartData = newChartData;
 
-    wss.clients.forEach((client) => {
+    for (const client of wss.clients) {
       if (client.readyState === WebSocket.OPEN) {
         client.send(
           JSON.stringify({
@@ -134,8 +121,14 @@ async function startServer(bundleStats, opts) {
           }),
         );
       }
-    });
+    }
   }
+
+  return {
+    ws: wss,
+    http: server,
+    updateChartData,
+  };
 }
 
 async function generateReport(bundleStats, opts) {
@@ -247,3 +240,12 @@ function getEntrypoints(bundleStats) {
     (entrypoint) => entrypoint.name,
   );
 }
+
+module.exports = {
+  generateJSONReport,
+  generateReport,
+  getEntrypoints,
+  // deprecated
+  start: startServer,
+  startServer,
+};
diff --git a/test/Logger.js b/test/Logger.js
index 916d769a..2a2cd3a7 100644
--- a/test/Logger.js
+++ b/test/Logger.js
@@ -17,11 +17,11 @@ class TestLogger extends Logger {
 
 let logger;
 
-describe("Logger", function () {
-  describe("level", function () {
+describe("Logger", () => {
+  describe("level", () => {
     for (const testingLevel of Logger.levels) {
-      describe(`"${testingLevel}"`, function () {
-        beforeEach(function () {
+      describe(`"${testingLevel}"`, () => {
+        beforeEach(() => {
           logger = new TestLogger(testingLevel);
         });
 
@@ -31,12 +31,12 @@ describe("Logger", function () {
           if (
             Logger.levels.indexOf(level) >= Logger.levels.indexOf(testingLevel)
           ) {
-            it(`should log "${level}" message`, function () {
+            it(`should log "${level}" message`, () => {
               logger[level]("msg1", "msg2");
               expect(logger.logs).toEqual([[level, "msg1", "msg2"]]);
             });
           } else {
-            it(`should not log "${level}" message`, function () {
+            it(`should not log "${level}" message`, () => {
               logger[level]("msg1", "msg2");
               expect(logger.logs).toHaveLength(0);
             });
@@ -45,12 +45,12 @@ describe("Logger", function () {
       });
     }
 
-    it('should be set to "info" by default', function () {
+    it('should be set to "info" by default', () => {
       logger = new TestLogger();
       expectLoggerLevel(logger, "info");
     });
 
-    it("should allow to change level", function () {
+    it("should allow to change level", () => {
       logger = new TestLogger("warn");
       expectLoggerLevel(logger, "warn");
       logger.setLogLevel("info");
@@ -59,13 +59,13 @@ describe("Logger", function () {
       expectLoggerLevel(logger, "silent");
     });
 
-    it("should throw if level is invalid on instance creation", function () {
+    it("should throw if level is invalid on instance creation", () => {
       expect(() => new TestLogger("invalid")).toThrow(
         invalidLogLevelMessage("invalid"),
       );
     });
 
-    it("should throw if level is invalid on `setLogLevel`", function () {
+    it("should throw if level is invalid on `setLogLevel`", () => {
       expect(() => new TestLogger().setLogLevel("invalid")).toThrow(
         invalidLogLevelMessage("invalid"),
       );
diff --git a/test/analyzer.js b/test/analyzer.js
index 6c1e78f1..9c17dbd8 100644
--- a/test/analyzer.js
+++ b/test/analyzer.js
@@ -1,43 +1,39 @@
-const fs = require("fs");
-const path = require("path");
-const childProcess = require("child_process");
+const childProcess = require("node:child_process");
+const fs = require("node:fs");
+const path = require("node:path");
 const puppeteer = require("puppeteer");
 const { isZstdSupported } = require("../src/sizeUtils");
 
 let browser;
 
-describe("Analyzer", function () {
-  jest.setTimeout(15000);
+jest.setTimeout(15000);
 
-  beforeAll(async function () {
+describe("Analyzer", () => {
+  beforeAll(async () => {
     browser = await puppeteer.launch();
-    await fs.promises.rm(`${__dirname}/output`, {
+    await fs.promises.rm(path.resolve(__dirname, "./output"), {
       force: true,
       recursive: true,
     });
   });
 
-  beforeEach(async function () {
-    jest.setTimeout(15000);
-  });
-
-  afterEach(async function () {
-    await fs.promises.rm(`${__dirname}/output`, {
+  afterEach(async () => {
+    await fs.promises.rm(path.resolve(__dirname, "./output"), {
       force: true,
       recursive: true,
     });
   });
 
-  afterAll(async function () {
+  afterAll(async () => {
     await browser.close();
   });
 
-  it("should support stats files with all the information in `children` array", async function () {
+  it("should support stats files with all the information in `children` array", async () => {
     generateReportFrom("with-children-array.json");
     await expectValidReport();
   });
 
-  it("should generate report containing worker bundles", async function () {
+  it("should generate report containing worker bundles", async () => {
     generateReportFrom("with-worker-loader/stats.json");
     const chartData = await getChartData();
     expect(chartData[1]).toMatchObject({
@@ -45,7 +41,7 @@ describe("Analyzer", function () {
     });
   });
 
-  it("should generate report for array webpack.config.js", async function () {
+  it("should generate report for array webpack.config.js", async () => {
     generateReportFrom("with-array-config/stats.json");
     const chartData = await getChartData();
     expect(chartData).toHaveLength(2);
@@ -57,7 +53,7 @@ describe("Analyzer", function () {
     });
   });
 
-  it("should generate report when worker bundles have dynamic imports", async function () {
+  it("should generate report when worker bundles have dynamic imports", async () => {
     generateReportFrom("with-worker-loader-dynamic-import/stats.json");
     const chartData = await getChartData();
     expect(chartData[1]).toMatchObject({
@@ -65,7 +61,7 @@ describe("Analyzer", function () {
     });
   });
 
-  it("should support stats files with modules inside `chunks` array", async function () {
+  it("should support stats files with modules inside `chunks` array", async () => {
     generateReportFrom("with-modules-in-chunks/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -73,7 +69,7 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should record accurate byte lengths for sources with special chars", async function () {
+  it("should record accurate byte lengths for sources with special chars", async () => {
     generateReportFrom("with-special-chars/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -81,12 +77,12 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should support bundles with invalid dynamic require calls", async function () {
+  it("should support bundles with invalid dynamic require calls", async () => {
     generateReportFrom("with-invalid-dynamic-require.json");
     await expectValidReport({ statSize: 136 });
   });
 
-  it("should use information about concatenated modules generated by webpack 4", async function () {
+  it("should use information about concatenated modules generated by webpack 4", async () => {
     generateReportFrom("with-module-concatenation-info/stats.json");
     const chartData = await getChartData();
     expect(chartData[0].groups[0]).toMatchObject(
@@ -94,13 +90,13 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should handle stats with minimal configuration", async function () {
+  it("should handle stats with minimal configuration", async () => {
     generateReportFrom("minimal-stats/stats.json");
     const chartData = await getChartData();
     expect(chartData).toHaveLength(0);
   });
 
-  it.skip("should not filter out modules that we couldn't find during parsing", async function () {
+  it.skip("should not filter out modules that we couldn't find during parsing", async () => {
     generateReportFrom("with-missing-parsed-module/stats.json");
     const chartData = await getChartData();
     let unparsedModules = 0;
@@ -112,7 +108,7 @@ describe("Analyzer", function () {
     expect(unparsedModules).toBe(1);
   });
 
-  it.skip("should gracefully parse invalid chunks", async function () {
+  it.skip("should gracefully parse invalid chunks", async () => {
     generateReportFrom("with-invalid-chunk/stats.json");
     const chartData = await getChartData();
     const invalidChunk = chartData.find((i) => i.label === "invalid-chunk.js");
@@ -128,7 +124,7 @@ describe("Analyzer", function () {
     expect(invalidChunk.parsedSize).toBe(30);
   });
 
-  it.skip("should gracefully process missing chunks", async function () {
+  it.skip("should gracefully process missing chunks", async () => {
     generateReportFrom("with-missing-chunk/stats.json");
     const chartData = await getChartData();
     const invalidChunk = chartData.find((i) => i.label === "invalid-chunk.js");
@@ -145,7 +141,7 @@ describe("Analyzer", function () {
     });
   });
 
-  it.skip("should gracefully process missing module chunks", async function () {
+  it.skip("should gracefully process missing module chunks", async () => {
     generateReportFrom("with-missing-module-chunks/stats.json");
     const chartData = await getChartData();
     const invalidChunk = chartData.find((i) => i.label === "invalid-chunk.js");
@@ -162,17 +158,17 @@ describe("Analyzer", function () {
     });
   });
 
-  it("should support stats files with js modules chunk", async function () {
+  it("should support stats files with js modules chunk", async () => {
     generateReportFrom("with-modules-chunk.json");
     await expectValidReport({ bundleLabel: "bundle.mjs" });
   });
 
-  it("should support stats files with cjs chunk", async function () {
+  it("should support stats files with cjs chunk", async () => {
     generateReportFrom("with-cjs-chunk.json");
     await expectValidReport({ bundleLabel: "bundle.cjs" });
   });
 
-  it("should properly parse extremely optimized bundle from webpack 5", async function () {
+  it("should properly parse extremely optimized bundle from webpack 5", async () => {
     generateReportFrom("extremely-optimized-webpack-5-bundle/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -180,7 +176,7 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should properly parse webpack 5 bundle with single entry", async function () {
+  it("should properly parse webpack 5 bundle with single entry", async () => {
     generateReportFrom("webpack-5-bundle-with-single-entry/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -188,7 +184,7 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should properly parse webpack 5 bundle with multiple entries", async function () {
+  it("should properly parse webpack 5 bundle with multiple entries", async () => {
     generateReportFrom("webpack-5-bundle-with-multiple-entries/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -196,7 +192,7 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should properly parse webpack 5 bundle with an entry module that is a concatenated module", async function () {
+  it("should properly parse webpack 5 bundle with an entry module that is a concatenated module", async () => {
     generateReportFrom(
       "webpack-5-bundle-with-concatenated-entry-module/stats.json",
     );
@@ -206,21 +202,22 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should support generating JSON output for the report", async function () {
+  it("should support generating JSON output for the report", async () => {
     generateJSONReportFrom("with-modules-in-chunks/stats.json");
 
     const chartData = require(path.resolve(__dirname, "output/report.json"));
+
     expect(chartData).toMatchObject(
       require("./stats/with-modules-in-chunks/expected-chart-data"),
     );
   });
 
-  it("should support stats files with non-asset asset", async function () {
+  it("should support stats files with non-asset asset", async () => {
     generateReportFrom("with-non-asset-asset/stats.json");
     await expectValidReport({ bundleLabel: "bundle.js" });
   });
 
-  it("should map chunks correctly to entrypoints", async function () {
+  it("should map chunks correctly to entrypoints", async () => {
     generateReportFrom("with-multiple-entrypoints/stats.json");
     const chartData = await getChartData();
     expect(chartData).toMatchObject(
@@ -228,15 +225,15 @@ describe("Analyzer", function () {
     );
   });
 
-  it("should return empty chartData if there are no entrypoints", async function () {
+  it("should return empty chartData if there are no entrypoints", async () => {
     generateReportFrom("with-no-entrypoints/stats.json");
     const chartData = await getChartData();
     expect(chartData).toHaveLength(0);
   });
 
-  describe("options", function () {
-    describe("title", function () {
-      it("should take the --title option", async function () {
+  describe("options", () => {
+    describe("title", () => {
+      it("should take the --title option", async () => {
         const reportTitle = "A string report title";
         generateReportFrom(
           "with-modules-chunk.json",
@@ -247,7 +244,8 @@ describe("Analyzer", function () {
 
         expect(generatedReportTitle).toBe(reportTitle);
       });
-      it("should take the -t option", async function () {
+
+      it("should take the -t option", async () => {
         const reportTitle = "A string report title";
 
         generateReportFrom("with-modules-chunk.json", `-t "${reportTitle}"`);
@@ -256,7 +254,8 @@ describe("Analyzer", function () {
 
         expect(generatedReportTitle).toBe(reportTitle);
       });
-      it("should use a suitable default title", async function () {
+
+      it("should use a suitable default title", async () => {
         generateReportFrom("with-modules-chunk.json");
 
         const generatedReportTitle = await getTitleFromReport();
@@ -267,8 +266,8 @@ describe("Analyzer", function () {
       });
     });
 
-    describe("compression algorithm", function () {
-      it("should accept --compression-algorithm brotli", async function () {
+    describe("compression algorithm", () => {
+      it("should accept --compression-algorithm brotli", async () => {
         generateReportFrom(
           "with-modules-chunk.json",
           "--compression-algorithm brotli",
@@ -276,7 +275,7 @@ describe("Analyzer", function () {
         expect(await getCompressionAlgorithm()).toBe("brotli");
       });
 
-      it("should accept --compression-algorithm gzip", async function () {
+      it("should accept --compression-algorithm gzip", async () => {
         generateReportFrom(
           "with-modules-chunk.json",
           "--compression-algorithm gzip",
@@ -285,7 +284,7 @@ describe("Analyzer", function () {
       });
 
       if (isZstdSupported) {
-        it("should accept --compression-algorithm zstd", async function () {
+        it("should accept --compression-algorithm zstd", async () => {
           generateReportFrom(
             "with-modules-chunk.json",
             "--compression-algorithm zstd",
@@ -294,7 +293,7 @@ describe("Analyzer", function () {
         });
       }
 
-      it("should default to gzip", async function () {
+      it("should default to gzip", async () => {
         generateReportFrom("with-modules-chunk.json");
         expect(await getCompressionAlgorithm()).toBe("gzip");
       });
diff --git a/test/dev-server.js b/test/dev-server.js
index 8d0e6f49..1a6388b7 100644
--- a/test/dev-server.js
+++ b/test/dev-server.js
@@ -1,22 +1,26 @@
-const fs = require("fs");
-const { spawn } = require("child_process");
+const { spawn } = require("node:child_process");
+const fs = require("node:fs");
+const path = require("node:path");
 
 const ROOT = `${__dirname}/dev-server`;
 const WEBPACK_CONFIG_PATH = `${ROOT}/webpack.config.js`;
+
 const webpackConfig = require(WEBPACK_CONFIG_PATH);
 
-describe("Webpack Dev Server", function () {
+const timeout = 15000;
+
+jest.setTimeout(timeout);
+
+describe("Webpack Dev Server", () => {
   beforeAll(deleteOutputDirectory);
-  afterEach(deleteOutputDirectory);
 
-  const timeout = 15000;
-  jest.setTimeout(timeout);
+  afterEach(deleteOutputDirectory);
 
-  it("should save report file to the output directory", function (done) {
+  it("should save report file to the output directory", (done) => {
     const startedAt = Date.now();
 
     const devServer = spawn(
-      `${__dirname}/../node_modules/.bin/webpack-dev-server`,
+      path.resolve(__dirname, "../node_modules/.bin/webpack-dev-server"),
       ["--config", WEBPACK_CONFIG_PATH],
       {
         cwd: ROOT,
@@ -24,7 +28,9 @@ describe("Webpack Dev Server", function () {
     );
 
     const reportCheckIntervalId = setInterval(() => {
-      if (fs.existsSync(`${webpackConfig.output.path}/report.html`)) {
+      if (
+        fs.existsSync(path.resolve(webpackConfig.output.path, "./report.html"))
+      ) {
         finish();
       } else if (Date.now() - startedAt > timeout - 1000) {
         finish(
diff --git a/test/dev-server/webpack.config.js b/test/dev-server/webpack.config.js
index b58912e6..45327b60 100644
--- a/test/dev-server/webpack.config.js
+++ b/test/dev-server/webpack.config.js
@@ -1,10 +1,13 @@
+"use strict";
+
+const path = require("node:path");
 const BundleAnalyzerPlugin = require("../../lib/BundleAnalyzerPlugin");
 
 module.exports = {
   mode: "development",
-  entry: `${__dirname}/src.js`,
+  entry: path.resolve(__dirname, "./src.js"),
   output: {
-    path: `${__dirname}/output`,
+    path: path.resolve(__dirname, "./output"),
     filename: "bundle.js",
   },
   plugins: [
diff --git a/test/helpers.js b/test/helpers.js
index fe4b8cc8..782c063d 100644
--- a/test/helpers.js
+++ b/test/helpers.js
@@ -1,4 +1,4 @@
-const { readdirSync } = require("fs");
+const { readdirSync } = require("node:fs");
 const webpack = require("webpack");
 
 global.webpackCompile = webpackCompile;
@@ -62,11 +62,11 @@ function forEachWebpackVersion(versions, cb) {
   }
 
   for (const version of versions) {
-    const itFn = function (testDescription, ...args) {
+    const itFn = function itFn(testDescription, ...args) {
       return it.call(this, `${testDescription} (Webpack ${version})`, ...args);
     };
 
-    itFn.only = function (testDescription, ...args) {
+    itFn.only = function only(testDescription, ...args) {
       return it.only.call(
         this,
         `${testDescription} (Webpack ${version})`,
@@ -101,6 +101,7 @@ async function webpackCompile(config, version) {
     throw new Error(
       `Error requiring Webpack ${version}:\n${err}\n\n` +
         'Try running "npm run install-test-webpack-versions".',
+      { cause: err },
     );
   }
 
@@ -130,7 +131,7 @@ function makeWebpackConfig(opts = {}) {
       analyzerMode: "static",
       openAnalyzer: false,
       logLevel: "error",
-      ...(opts.analyzerOpts || {}),
+      ...opts.analyzerOpts,
     },
   };
 
@@ -171,5 +172,7 @@ function makeWebpackConfig(opts = {}) {
 }
 
 function wait(ms) {
-  return new Promise((resolve) => setTimeout(resolve, ms));
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
 }
diff --git a/test/parseUtils.js b/test/parseUtils.js
index 05eb2995..5bb1b884 100644
--- a/test/parseUtils.js
+++ b/test/parseUtils.js
@@ -1,31 +1,32 @@
-const fs = require("fs");
+const fs = require("node:fs");
+const path = require("node:path");
 
 const { parseBundle } = require("../lib/parseUtils");
 
-const BUNDLES_DIR = `${__dirname}/bundles`;
+const BUNDLES_DIR = path.resolve(__dirname, "./bundles");
 
-describe("parseBundle", function () {
+describe("parseBundle", () => {
   const bundles = fs
     .readdirSync(BUNDLES_DIR)
     .filter((filename) => filename.endsWith(".js"))
     .map((filename) => filename.replace(/\.js$/u, ""));
 
-  bundles
-    .filter((bundleName) => bundleName.startsWith("valid"))
-    .forEach((bundleName) => {
-      it(`should parse ${bundleName.toLocaleLowerCase()}`, function () {
-        const bundleFile = `${BUNDLES_DIR}/${bundleName}.js`;
-        const bundle = parseBundle(bundleFile);
-        const expectedModules = JSON.parse(
-          fs.readFileSync(`${BUNDLES_DIR}/${bundleName}.modules.json`),
-        );
+  for (const bundleName of bundles.filter((bundleName) =>
+    bundleName.startsWith("valid"),
+  )) {
+    it(`should parse ${bundleName.toLocaleLowerCase()}`, () => {
+      const bundleFile = `${BUNDLES_DIR}/${bundleName}.js`;
+      const bundle = parseBundle(bundleFile);
+      const expectedModules = JSON.parse(
+        fs.readFileSync(`${BUNDLES_DIR}/${bundleName}.modules.json`),
+      );
 
-        expect(bundle.src).toBe(fs.readFileSync(bundleFile, "utf8"));
-        expect(bundle.modules).toEqual(expectedModules.modules);
-      });
+      expect(bundle.src).toBe(fs.readFileSync(bundleFile, "utf8"));
+      expect(bundle.modules).toEqual(expectedModules.modules);
     });
+  }
 
-  it("should parse invalid bundle and return it's content and empty modules hash", function () {
+  it("should parse invalid bundle and return it's content and empty modules hash", () => {
     const bundleFile = `${BUNDLES_DIR}/invalidBundle.js`;
     const bundle = parseBundle(bundleFile);
     expect(bundle.src).toBe(fs.readFileSync(bundleFile, "utf8"));
diff --git a/test/plugin.js b/test/plugin.js
index d844a7e8..67a8afca 100644
--- a/test/plugin.js
+++ b/test/plugin.js
@@ -1,32 +1,33 @@
-const fs = require("fs");
-const path = require("path");
+const fs = require("node:fs");
+const path = require("node:path");
 const puppeteer = require("puppeteer");
 const BundleAnalyzerPlugin = require("../lib/BundleAnalyzerPlugin");
 const { isZstdSupported } = require("../src/sizeUtils");
 
-describe("Plugin", function () {
-  describe("options", function () {
-    it("should be optional", function () {
+jest.setTimeout(15000);
+
+describe("Plugin", () => {
+  describe("options", () => {
+    it("should be optional", () => {
       expect(() => new BundleAnalyzerPlugin()).not.toThrow();
     });
   });
 });
 
-describe("Plugin", function () {
+describe("Plugin", () => {
   let browser;
-  jest.setTimeout(15000);
 
-  beforeEach(async function () {
+  beforeEach(async () => {
     browser = await puppeteer.launch();
-    await fs.promises.rm(`${__dirname}/output`, {
+    await fs.promises.rm(path.resolve(__dirname, "./output"), {
       force: true,
       recursive: true,
     });
   });
 
-  afterEach(async function () {
+  afterEach(async () => {
     await browser.close();
-    await fs.promises.rm(`${__dirname}/output`, {
+    await fs.promises.rm(path.resolve(__dirname, "./output"), {
       force: true,
       recursive: true,
     });
@@ -34,7 +35,7 @@ describe("Plugin", function () {
 
   forEachWebpackVersion(["4.44.2"], ({ it, webpackCompile }) => {
     // Webpack 5 doesn't support `jsonpFunction` option
-    it("should support webpack config with custom `jsonpFunction` name", async function () {
+    it("should support webpack config with custom `jsonpFunction` name", async () => {
       const config = makeWebpackConfig({
         multipleChunks: true,
       });
@@ -51,7 +52,7 @@ describe("Plugin", function () {
   });
 
   forEachWebpackVersion(({ it, webpackCompile }) => {
-    it("should allow to generate json report", async function () {
+    it("should allow to generate json report", async () => {
       const config = makeWebpackConfig({
         analyzerOpts: {
           analyzerMode: "json",
@@ -64,7 +65,7 @@ describe("Plugin", function () {
       expect(chartData).toBeDefined();
     });
 
-    it("should support webpack config with `multi` module", async function () {
+    it("should support webpack config with `multi` module", async () => {
       const config = makeWebpackConfig();
 
       config.entry.bundle = ["./src/a.js", "./src/b.js"];
@@ -97,10 +98,10 @@ describe("Plugin", function () {
     });
   });
 
-  describe("options", function () {
-    describe("excludeAssets", function () {
+  describe("options", () => {
+    describe("excludeAssets", () => {
       forEachWebpackVersion(({ it, webpackCompile }) => {
-        it("should filter out assets from the report", async function () {
+        it("should filter out assets from the report", async () => {
           const config = makeWebpackConfig({
             multipleChunks: true,
             analyzerOpts: {
@@ -116,8 +117,8 @@ describe("Plugin", function () {
       });
     });
 
-    describe("reportTitle", function () {
-      it("should have a sensible default", async function () {
+    describe("reportTitle", () => {
+      it("should have a sensible default", async () => {
         const config = makeWebpackConfig();
         await webpackCompile(config, "4.44.2");
         const generatedReportTitle = await getTitleFromReport();
@@ -126,7 +127,7 @@ describe("Plugin", function () {
         );
       });
 
-      it("should support a string value", async function () {
+      it("should support a string value", async () => {
         const reportTitle = "A string report title";
         const config = makeWebpackConfig({
           analyzerOpts: {
@@ -138,7 +139,7 @@ describe("Plugin", function () {
         expect(generatedReportTitle).toBe(reportTitle);
       });
 
-      it("should support a function value", async function () {
+      it("should support a function value", async () => {
         const reportTitleResult = "A string report title";
         const config = makeWebpackConfig({
           analyzerOpts: {
@@ -150,7 +151,7 @@ describe("Plugin", function () {
         expect(generatedReportTitle).toBe(reportTitleResult);
       });
 
-      it("should propagate an error in a function", async function () {
+      it("should propagate an error in a function", async () => {
         const reportTitleError = new Error();
         const config = makeWebpackConfig({
           analyzerOpts: {
@@ -163,22 +164,22 @@ describe("Plugin", function () {
         let error = null;
         try {
           await webpackCompile(config, "4.44.2");
-        } catch (e) {
-          error = e;
+        } catch (err) {
+          error = err;
         }
 
         expect(error).toBe(reportTitleError);
       });
     });
 
-    describe("compressionAlgorithm", function () {
-      it("should default to gzip", async function () {
+    describe("compressionAlgorithm", () => {
+      it("should default to gzip", async () => {
         const config = makeWebpackConfig({ analyzerOpts: {} });
         await webpackCompile(config, "4.44.2");
         await expectValidReport({ parsedSize: 1317, gzipSize: 341 });
       });
 
-      it("should support gzip", async function () {
+      it("should support gzip", async () => {
         const config = makeWebpackConfig({
           analyzerOpts: { compressionAlgorithm: "gzip" },
         });
@@ -186,7 +187,7 @@ describe("Plugin", function () {
         await expectValidReport({ parsedSize: 1317, gzipSize: 341 });
       });
 
-      it("should support brotli", async function () {
+      it("should support brotli", async () => {
         const config = makeWebpackConfig({
           analyzerOpts: { compressionAlgorithm: "brotli" },
         });
@@ -197,8 +198,9 @@ describe("Plugin", function () {
           brotliSize: 295,
         });
       });
+
       if (isZstdSupported) {
-        it("should support zstd", async function () {
+        it("should support zstd", async () => {
           const config = makeWebpackConfig({
             analyzerOpts: { compressionAlgorithm: "zstd" },
           });
@@ -224,8 +226,12 @@ describe("Plugin", function () {
       gzipSize,
     } = { gzipSize: 770, ...opts };
 
-    expect(fs.existsSync(`${__dirname}/output/${bundleFilename}`)).toBe(true);
-    expect(fs.existsSync(`${__dirname}/output/${reportFilename}`)).toBe(true);
+    expect(
+      fs.existsSync(path.resolve(__dirname, `/output/${bundleFilename}`)),
+    ).toBe(true);
+    expect(
+      fs.existsSync(path.resolve(__dirname, `/output/${reportFilename}`)),
+    ).toBe(true);
     const chartData = await getChartDataFromReport(reportFilename);
 
     const expected = {
diff --git a/test/statsUtils.js b/test/statsUtils.js
index 1a59551c..9bfd2dbc 100644
--- a/test/statsUtils.js
+++ b/test/statsUtils.js
@@ -1,11 +1,25 @@
-const path = require("path");
-const { readFileSync } = require("fs");
+const { readFileSync } = require("node:fs");
+const path = require("node:path");
 const { globSync } = require("tinyglobby");
-
 const { StatsSerializeStream } = require("../lib/statsUtils");
 
+async function stringify(json) {
+  return new Promise((resolve, reject) => {
+    let result = "";
+
+    new StatsSerializeStream(json)
+      .on("data", (chunk) => (result += chunk))
+      .on("end", () => resolve(result))
+      .on("error", reject);
+  });
+}
+
+async function expectProperJson(json) {
+  expect(await stringify(json)).toBe(JSON.stringify(json, null, 2));
+}
+
 describe("StatsSerializeStream", () => {
-  it("should properly stringify primitives", function () {
+  it("should properly stringify primitives", () => {
     expectProperJson(0);
     expectProperJson(1);
     expectProperJson(-1);
@@ -22,7 +36,7 @@ describe("StatsSerializeStream", () => {
     expectProperJson("Вива Лас-Вегас!");
   });
 
-  it("should properly stringify simple arrays", function () {
+  it("should properly stringify simple arrays", () => {
     expectProperJson([]);
     expectProperJson([1, undefined, 2]);
     // eslint-disable-next-line
@@ -30,7 +44,7 @@ describe("StatsSerializeStream", () => {
     expectProperJson([false, "f'o\"o", -1, 42.42]);
   });
 
-  it("should properly stringify objects", function () {
+  it("should properly stringify objects", () => {
     expectProperJson({});
     expectProperJson({
       a: 1,
@@ -40,7 +54,7 @@ describe("StatsSerializeStream", () => {
     });
   });
 
-  it("should properly stringify complex structures", function () {
+  it("should properly stringify complex structures", () => {
     expectProperJson({
       foo: [],
       bar: {
@@ -56,26 +70,11 @@ describe("StatsSerializeStream", () => {
     });
   });
 
-  globSync("stats/**/*.json", { cwd: __dirname }).forEach((filepath) => {
-    it(`should properly stringify JSON from "${filepath}"`, function () {
+  for (const filepath of globSync("stats/**/*.json", { cwd: __dirname })) {
+    it(`should properly stringify JSON from "${filepath}"`, () => {
       const content = readFileSync(path.resolve(__dirname, filepath), "utf8");
       const json = JSON.parse(content);
       expectProperJson(json);
     });
-  });
+  }
 });
-
-async function expectProperJson(json) {
-  expect(await stringify(json)).toBe(JSON.stringify(json, null, 2));
-}
-
-async function stringify(json) {
-  return new Promise((resolve, reject) => {
-    let result = "";
-
-    new StatsSerializeStream(json)
-      .on("data", (chunk) => (result += chunk))
-      .on("end", () => resolve(result))
-      .on("error", reject);
-  });
-}
diff --git a/test/utils.js b/test/utils.js
index f4a67ca6..56ee626a 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -1,14 +1,14 @@
 const { createAssetsFilter } = require("../lib/utils");
 
-describe("createAssetsFilter", function () {
-  it("should create a noop filter if pattern is not set", function () {
+describe("createAssetsFilter", () => {
+  it("should create a noop filter if pattern is not set", () => {
     for (const pattern of [undefined, null, []]) {
       const filter = createAssetsFilter(pattern);
       expect(filter("foo")).toBe(true);
     }
   });
 
-  it("should allow a string as a pattern", function () {
+  it("should allow a string as a pattern", () => {
     const filter = createAssetsFilter("^foo");
     expect(filter("foo")).toBe(false);
     expect(filter("foo-bar")).toBe(false);
@@ -16,7 +16,7 @@ describe("createAssetsFilter", function () {
     expect(filter("bar-foo")).toBe(true);
   });
 
-  it("should allow a RegExp as a pattern", function () {
+  it("should allow a RegExp as a pattern", () => {
     const filter = createAssetsFilter(/^foo/iu);
     expect(filter("foo")).toBe(false);
     expect(filter("FOO")).toBe(false);
@@ -25,7 +25,7 @@ describe("createAssetsFilter", function () {
     expect(filter("bar-foo")).toBe(true);
   });
 
-  it("should allow a filter function as a pattern", function () {
+  it("should allow a filter function as a pattern", () => {
     const filter = createAssetsFilter((asset) => asset.startsWith("foo"));
     expect(filter("foo")).toBe(false);
     expect(filter("foo-bar")).toBe(false);
@@ -33,13 +33,13 @@ describe("createAssetsFilter", function () {
     expect(filter("bar-foo")).toBe(true);
   });
 
-  it("should throw on invalid pattern types", function () {
+  it("should throw on invalid pattern types", () => {
     expect(() => createAssetsFilter(5)).toThrow('but "5" got');
     expect(() => createAssetsFilter({ a: 1 })).toThrow('but "{ a: 1 }" got');
     expect(() => createAssetsFilter([true])).toThrow('but "true" got');
   });
 
-  it("should allow an array of patterns", function () {
+  it("should allow an array of patterns", () => {
     const filter = createAssetsFilter([
       "^foo",
       /bar$/iu,
diff --git a/test/viewer.js b/test/viewer.js
index e2b860db..5d355eaa 100644
--- a/test/viewer.js
+++ b/test/viewer.js
@@ -1,11 +1,11 @@
-const crypto = require("crypto");
-const net = require("net");
+const crypto = require("node:crypto");
+const net = require("node:net");
 
 const Logger = require("../lib/Logger");
-const { getEntrypoints, startServer } = require("../lib/viewer.js");
+const { getEntrypoints, startServer } = require("../lib/viewer");
 
-describe("WebSocket server", function () {
-  it("should not crash when an error is emitted on the websocket", function (done) {
+describe("WebSocket server", () => {
+  it("should not crash when an error is emitted on the websocket", (done) => {
     const bundleStats = {
       assets: [{ name: "bundle.js", chunks: [0] }],
     };
@@ -18,7 +18,7 @@ describe("WebSocket server", function () {
     };
 
     startServer(bundleStats, options)
-      .then(function ({ http: server }) {
+      .then(({ http: server }) => {
         // The GUID constant defined in WebSocket protocol
         // https://tools.ietf.org/html/rfc6455#section-1.3
         const GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
@@ -32,7 +32,7 @@ describe("WebSocket server", function () {
           .update(key + GUID)
           .digest("base64");
 
-        const socket = net.createConnection(server.address().port, function () {
+        const socket = net.createConnection(server.address().port, () => {
           socket.write(
             [
               "GET / HTTP/1.1",
@@ -47,12 +47,12 @@ describe("WebSocket server", function () {
           );
         });
 
-        socket.on("close", function () {
+        socket.on("close", () => {
           server.close(done);
         });
 
         let count = 0;
-        socket.on("data", function (chunk) {
+        socket.on("data", (chunk) => {
           ++count;
           const expected = Buffer.from(
             [
@@ -109,19 +109,19 @@ describe("getEntrypoints", () => {
     );
   });
 
-  it("should handle when bundlestats is null or undefined ", function () {
+  it("should handle when bundlestats is null or undefined", () => {
     expect(JSON.stringify(getEntrypoints(null))).toBe(JSON.stringify([]));
     expect(JSON.stringify(getEntrypoints(undefined))).toBe(JSON.stringify([]));
   });
 
-  it("should handle when bundlestats is empty", function () {
+  it("should handle when bundlestats is empty", () => {
     const bundleStatsWithoutEntryPoints = {};
     expect(JSON.stringify(getEntrypoints(bundleStatsWithoutEntryPoints))).toBe(
       JSON.stringify([]),
     );
   });
 
-  it("should handle when entrypoints is empty", function () {
+  it("should handle when entrypoints is empty", () => {
     const bundleStatsEmptyEntryPoint = { entrypoints: {} };
     expect(JSON.stringify(getEntrypoints(bundleStatsEmptyEntryPoint))).toBe(
       JSON.stringify([]),
diff --git a/webpack.config.js b/webpack.config.js
index 9b42441a..e230383e 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -1,5 +1,8 @@
-const webpack = require("webpack");
+"use strict";
+
+const path = require("node:path");
 const TerserPlugin = require("terser-webpack-plugin");
+const webpack = require("webpack");
 const BundleAnalyzePlugin = require("./lib/BundleAnalyzerPlugin");
 
 const isDev = (process.env.NODE_ENV || "production") === "development";
@@ -8,14 +11,13 @@ const needAnalyze = process.env.ANALYZE || false;
 module.exports = {
   mode: process.env.NODE_ENV || "production",
   context: __dirname,
-  entry: "./client/viewer",
+  entry: "./client/viewer.jsx",
   output: {
-    path: `${__dirname}/public`,
+    path: path.resolve(__dirname, "./public"),
     filename: "viewer.js",
     publicPath: "/",
   },
   resolve: {
-    extensions: [".js", ".jsx"],
     alias: {
       react: "preact/compat",
       "react-dom/test-utils": "preact/test-utils",

From 7bc5ea6e61298a609aa40fd82dc124cfa888b610 Mon Sep 17 00:00:00 2001
From: alexander-akait <sheo13666q@gmail.com>
Date: Wed, 28 Jan 2026 16:04:53 +0300
Subject: [PATCH 2/3] test: fix

---
 test/plugin.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/plugin.js b/test/plugin.js
index 67a8afca..c06e8c8f 100644
--- a/test/plugin.js
+++ b/test/plugin.js
@@ -227,10 +227,10 @@ describe("Plugin", () => {
     } = { gzipSize: 770, ...opts };
 
     expect(
-      fs.existsSync(path.resolve(__dirname, `/output/${bundleFilename}`)),
+      fs.existsSync(path.resolve(__dirname, `./output/${bundleFilename}`)),
     ).toBe(true);
     expect(
-      fs.existsSync(path.resolve(__dirname, `/output/${reportFilename}`)),
+      fs.existsSync(path.resolve(__dirname, `./output/${reportFilename}`)),
     ).toBe(true);
     const chartData = await getChartDataFromReport(reportFilename);
 

From c215ce73a2fcc6d77636bfc73418ed862878d435 Mon Sep 17 00:00:00 2001
From: alexander-akait <sheo13666q@gmail.com>
Date: Fri, 30 Jan 2026 12:36:13 +0300
Subject: [PATCH 3/3] refactor: fix

---
 src/utils.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/utils.js b/src/utils.js
index 2cb94f8a..32bd5a8a 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -46,15 +46,15 @@ function createAssetsFilter(excludePatterns) {
   return () => true;
 }
 
-/**
- * @desc get string of current time
- * format: dd/MMM HH:mm
- * */
 function defaultAnalyzerUrl(options) {
   const { listenHost, boundAddress } = options;
   return `http://${listenHost}:${boundAddress.port}`;
 }
 
+/**
+ * @desc get string of current time
+ * format: dd/MMM HH:mm
+ * */
 function defaultTitle() {
   const time = new Date();
   const year = time.getFullYear();