JavaScript Interview Questions & Answers

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No.	Questions
1	What are the possible ways to create objects in JavaScript
2	What is a prototype chain
3	What is the difference between Call, Apply and Bind
4	What is JSON and its common operations
5	What is the purpose of the array slice method
6	What is the purpose of the array splice method
7	What is the difference between slice and splice
8	How do you compare Object and Map
9	What is the difference between == and === operators
10	What are lambda expressions or arrow functions
11	What is a first class function
12	What is a first order function
13	What is a higher order function
14	What is a unary function
15	What is the currying function
16	What is a pure function
17	What is the purpose of the let keyword
18	What is the difference between let and var
19	What is the reason to choose the name let as a keyword
20	How do you redeclare variables in a switch block without an error
21	What is the Temporal Dead Zone
22	What is an IIFE (Immediately Invoked Function Expression)
23	How do you decode or encode a URL in JavaScript?
24	What is memoization
25	What is Hoisting
26	What are classes in ES6
27	What are closures
28	What are modules
29	Why do you need modules
30	What is scope in javascript
31	What is a service worker
32	How do you manipulate DOM using a service worker
33	How do you reuse information across service worker restarts
34	What is IndexedDB
35	What is web storage
36	What is a post message
37	What is a Cookie
38	Why do you need a Cookie
39	What are the options in a cookie
40	How do you delete a cookie
41	What are the differences between cookie, local storage and session storage
42	What is the main difference between localStorage and sessionStorage
43	How do you access web storage
44	What are the methods available on session storage
45	What is a storage event and its event handler
46	Why do you need web storage
47	How do you check web storage browser support
48	How do you check web workers browser support
49	Give an example of a web worker
50	What are the restrictions of web workers on DOM
51	What is a promise
52	Why do you need a promise
53	What are the three states of promise
54	What is a callback function
55	Why do we need callbacks
56	What is a callback hell
57	What are server-sent events
58	How do you receive server-sent event notifications
59	How do you check browser support for server-sent events
60	What are the events available for server sent events
61	What are the main rules of promise
62	What is callback in callback
63	What is promise chaining
64	What is promise.all
65	What is the purpose of the race method in promise
66	What is a strict mode in javascript
67	Why do you need strict mode
68	How do you declare strict mode
69	What is the purpose of double exclamation
70	What is the purpose of the delete operator
71	What is typeof operator
72	What is undefined property
73	What is null value
74	What is the difference between null and undefined
75	What is eval
76	What is the difference between window and document
77	How do you access history in javascript
78	How do you detect caps lock key turned on or not
79	What is isNaN
80	What are the differences between undeclared and undefined variables
81	What are global variables
82	What are the problems with global variables
83	What is NaN property
84	What is the purpose of isFinite function
85	What is an event flow
86	What is event bubbling
87	What is event capturing
88	How do you submit a form using JavaScript
89	How do you find operating system details
90	What is the difference between document load and DOMContentLoaded events
91	What is the difference between native, host and user objects
92	What are the tools or techniques used for debugging JavaScript code
93	What are the pros and cons of promises over callbacks
94	What is the difference between an attribute and a property
95	What is same-origin policy
96	What is the purpose of void 0
97	Is JavaScript a compiled or interpreted language
98	Is JavaScript a case-sensitive language
99	Is there any relation between Java and JavaScript
100	What are events
101	Who created javascript
102	What is the use of preventDefault method
103	What is the use of stopPropagation method
104	What are the steps involved in return false usage
105	What is BOM
106	What is the use of setTimeout
107	What is the use of setInterval
108	Why is JavaScript treated as Single threaded
109	What is an event delegation
110	What is ECMAScript
111	What is JSON
112	What are the syntax rules of JSON
113	What is the purpose JSON stringify
114	How do you parse JSON string
115	Why do you need JSON
116	What are PWAs
117	What is the purpose of clearTimeout method
118	What is the purpose of clearInterval method
119	How do you redirect new page in javascript
120	How do you check whether a string contains a substring
121	How do you validate an email in javascript
122	How do you get the current url with javascript
123	What are the various url properties of location object
124	How do get query string values in javascript
125	How do you check if a key exists in an object
126	How do you loop through or enumerate javascript object
127	How do you test for an empty object
128	What is an arguments object
129	How do you make first letter of the string in an uppercase
130	What are the pros and cons of for loops
131	How do you display the current date in javascript
132	How do you compare two date objects
133	How do you check if a string starts with another string
134	How do you trim a string in javascript
135	[How do you add a key value pair in