@@ -27,17 +27,70 @@ Top JavaScript interview questions
2727| 19 | [ Difference between Call, apply, bind] ( #19-difference-between-call-apply-bind ) |
2828
2929### 1. What is JavaScript
30+ * JavaScript is the world's most popular programming language used for web development. It can be used to update HTML and CSS
31+ * Nowadays, JavaScript is getting used in many other areas e.g. server-side development, mobile app development etc.
3032
3133### 2. What are the different data types in JavaScript
34+ | Primitive | Non-primitive |
35+ | ------------- | ------------- |
36+ | Boolean, NULL, undefined, BigInt, String, Number, Symbol | Object |
3237
3338### 3. What are the different ways to create an Object in JavaScript
3439
40+ ##### a) Object Literals: A comma-separated set of name and value pairs that is wrapped inside curly braces.
41+ 42+ ```
43+ var person = {
44+ name: 'Surbhi',
45+ age: 25,
46+ occupation: 'Software Engineer'
47+ }
48+ ```
49+ ##### b) Object.create method: TCreates a new object, by using an existing object as the prototype of the newly created object.
50+ 51+ ```
52+ const person = {
53+ name: 'Surbhi',
54+ age: 25,
55+ occupation: 'Software Engineer'
56+ }
57+
58+ var info = Object.create(person);
59+ console.log(info.name); // output - Surbhi
60+
61+ Here "person" is an existing object which is passed as a prototype to the newly created object "info"
62+ ```
63+ 64+ ##### c) Object constructor: Constructor function allows to create objects with the help of new keyword
65+ 66+ ```
67+ const person = new Person();
68+ ```
69+ 70+ ##### d) using ES6: We can create object using ES6 class feature
71+ 72+ ```
73+ class Person {
74+ constructor(name) {
75+ this.name = name;
76+ }
77+ }
78+
79+ let person = new Person('Surbhi');
80+
81+ console.log(person.name); //output - Surbhi
82+ ```
83+ 3584### 4. Difference between "==" and "===" operators
85+ * == : While comparing two operands, checks for only value
86+ * === : While comparing two operands, checks for value as well as data type
3687
3788### 5. Is javascript single-threaded or multi-threaded
89+ * JavaScript is Single-threaded
3890
3991### 6. What are arrow functions and its features
4092
93+ 4194### 7. Explain passed by value and passed by reference
4295
4396### 8. What do you mean by Synthetic events
@@ -51,6 +104,13 @@ Top JavaScript interview questions
51104### 12. What are promises
52105
53106### 13. Can we combine two arrays using any es6 operators
107+ * Yes, using Spread Operators
108+ ```
109+ const arr1 = [1,2,3,4];
110+ const arr2 = [5,6];
111+ const arr3 = [...arr1, ...arr2]
112+ console.log(arr3) //output - [1,2,3,4,5,6]
113+ ```
54114
55115### 14. Difference between let, var, const
56116
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