added coding shortcut, output, function questions and memory garbage collection

Author: lgope

Interview-Questions/func.js

@@ -1,30 +1,29 @@
 // what is output?
 const foo = () => {
-  let a = b = 10;
+  let a = (b = 10);
   a++;
-  return a
-}
+  return a;
+};
 
 foo();
 
 console.log(a);
 console.log(b);
 
-
 // output
 function createIncrement() {
-	let count = 0;
+  let count = 0;
 
-	function increment() {
-		count++;
-	}
+  function increment() {
+    count++;
+  }
 
-	let message = `Count is ${count}`;
-	function log() {
-		console.log(message);
-	}
+  let message = `Count is ${count}`;
+  function log() {
+    console.log(message);
+  }
 
-	return [increment, log];
+  return [increment, log];
 }
 
 const [increment, log] = createIncrement();
@@ -36,22 +35,29 @@ increment();
 log();
 
 // Console sequence output?
-function run () {
+function run() {
   const promise = new Promise((resolve) => {
-    resolve('promise');
-  })
+    resolve("promise");
+  });
 
   setTimeout(() => {
-   console.log('setTimeout'); 
+    console.log("setTimeout");
   });
 
-  promise.then(res => console.log(res))
+  promise.then((res) => console.log(res));
 
-  console.log('log');
+  console.log("log");
 }
 
 run();
 
 // How does the Javascript interprets the following code?
 console.log(x);
 var x = 100;
+
+// Output
+(function () {
+  var a = (b = 5);
+})();
+
+console.log(b);

Interview-Questions/output.js

@@ -62,3 +62,87 @@ const array = [NaN];
 
 const result = array.includes(NaN);
 console.log(result); // True: why? => array.includes follows sameValueZero algorithm
+
+// Output
+const p = Promise.resolve("Hello");
+p.then((val) => {
+  console.log(val);
+  return `${val} world`;
+}).then((newVal) => {
+  console.log("new ", newVal);
+});
+
+// Output => level => easy
+function* counter() {
+  let index = 0;
+  while (true) {
+    yield index++;
+  }
+}
+
+const gen = counter();
+
+console.log(gen.next().value);
+console.log(gen.next().value);
+console.log(gen.next().value);
+
+// Output
+var y = 1;
+if (function f() {}) {
+  y += typeof f;
+}
+
+console.log(y);
+
+// Output
+var k = 1;
+if (1) {
+  eval(function foo() {});
+  k += typeof foo;
+}
+
+console.log(k);
+
+// Output
+var k = 1;
+if (1) {
+  function foo() {}
+  k += typeof foo;
+}
+console.log(k);
+
+// Write a function that would allow you to do this 👉🏻 multiply(5)(6)
+
+// Ans:
+function multiply(a) {
+  return function (b) {
+    return a * b;
+  };
+}
+
+multiply(5)(6);
+
+// Explain what is callback function is and provide a simple example
+
+function modifyArray(arr, callback) {
+  arr.push(100);
+
+  callback();
+}
+
+let arr = [1, 2, 3, 4, 5];
+
+modifyArray(arr, () => {
+  console.log("Array has been modified ", arr);
+});
+
+// Given a string, reverse each word in the sentence
+const reverseBySeparator = (str, separator) =>
+  str.split(separator).reverse().join(separator);
+
+const str = "Welcome to this Javascript Guide!";
+const reverseEntireSentence = reverseBySeparator(str, "");
+
+const reverseEachWord = reverseBySeparator(reverseEntireSentence, " ");
+
+console.log(reverseEntireSentence, reverseEachWord);

Memory/garbageCollection.js

@@ -0,0 +1,21 @@
+/**
+ * Garbage collection algorithms
+ * - Reference counting algorithm
+ * - Mark and sweep algorithm
+ */
+
+let obj = { a: 10 };
+obj = null;
+
+function test() {
+  let testObj = {};
+  let testObj2 = {};
+
+  //   Circular dependency
+  testObj.key = testObj2;
+  testObj2.key = testObj;
+
+  return "blah";
+}
+
+test();

js-coding-technique/asyncAwait.js

@@ -0,0 +1,21 @@
+// Best Practice
+async function getAddress() {
+  const streetAddress = await getStreetAddress();
+  const city = await getCity();
+  const state = await getState();
+  const zip = await getZip();
+
+  return `${streetAddress}, ${city}, ${state}, ${zip}`;
+}
+
+// Instated
+async function getAddress() {
+  let [streetAddress, city, state, zip] = await Promise.all([
+    getStreetAddress(),
+    getCity(),
+    getState(),
+    getZip(),
+  ]);
+
+  return `${streetAddress}, ${city}, ${state}, ${zip}`;
+}