javascript string problem solving

Author: lgope

Interview-Questions/queryString.js

@@ -0,0 +1,88 @@
+/**
+ * 1st case
+ * input: '?foo=hello&bar=world'
+ output: {
+    foo: 'hello',
+    bar: 'world'
+ }
+
+ * 2nd case
+ * input: '?' (if there is no query after ?)
+   output: should be an empty object like this 👉🏻 {}
+
+ * 3rd case
+ * input: '?foo=hello&bar=world&baz' (if there is no equal sign)
+  output: {
+    foo: 'hello',
+    bar: 'world',
+    baz: 'true' // send by default true as string
+ }
+
+ * 4th case
+ * input: '?foo=hello&bar=world&baz&foo=again' (if there is value with the same key, have to save values as array item)
+  output: {
+    foo: ['hello', 'again], // save value as array item whick belong to save key
+    bar: 'world',
+    baz: 'true'
+}
+
+ */
+
+const formatQueryString = (str) => {
+  //   strip off ? and then split by &
+  const query = str.slice(1).split("&");
+  const resObj = {};
+
+  //   iterate through key value pairs, split on = , and save in res object as key value
+  for (const pair of query) {
+    let [key, value] = pair.split("=");
+
+    // check if key truthy else send empty object (2nd case)
+    if (key) {
+      value = value || "true"; // checking value is truthy or undefined else befault 'true' value (3rd case)
+
+      // if there is value with the same key, have to save values as array item (4th case)
+      resObj[key] = resObj[key]
+        ? typeof resObj[key] === "string"
+          ? [resObj[key], value]
+          : [...resObj[key], value]
+        : value;
+
+      //   resObj[key] = resObj[key]
+      //     ? Array.isArray(resObj[key])
+      //     ? [...resObj[key], value]
+      //       : [resObj[key], value]
+      //     : value;
+    }
+  }
+
+  return resObj;
+};
+
+// console.log("1st case: ", formatQueryString("?foo=hello&bar=world"), {
+//     foo: 'hello',
+//     bar: 'world'
+//  });
+// console.log("2nd case: ", formatQueryString("?"), {}); // if there is no query after ?
+// console.log("3rd case: ", formatQueryString("?foo=hello&bar=world&baz"), {
+//   foo: "hello",
+//   bar: "world",
+//   baz: "true",
+// });
+
+/*console.log(
+  "4th case: ",
+  formatQueryString("?foo=hello&bar=world&baz&foo=again&foo=ok&bar=again&baz&dummy&data=earth"),
+  {
+    foo: [ 'hello', 'again', 'ok' ],
+  bar: [ 'world', 'again' ],
+  baz: [ 'true', 'true' ],
+  dummy: 'true',
+  data: 'earth'
+  }
+); */
+
+// test case
+console.log("4th case: ", formatQueryString("?foo=hello&foo"), {
+  foo: ["hello", "true"],
+});