• Book Name: JavaScript Interview Questions and Answers
• Author: Pratik Bandal
• Pages: 64
• Size:1 MB

Contents of JavaScript Interview Questions

1. Fundamentals

1. What is Javascript?
2. What are features of Javascript?
3. What are advantages of Javascript?
4. What are disadvantages of Javascript?
5. What is difference between Javascript and ECMAScript?
6. Who developed Javascript?
7. How to insert Javascript in Web page?
8. What are advantages of using external javascript?
9. Is Javascript case sensitive language?
10. Is Semicolon compulsory in Javascript at end of the statement?
11. What are different data types in Javascript?
12. How to add comment?
13. What is Javascript engine?
14. What are different Javascript frameworks that you know?

2. Variables, Operators and Statements

15. Explain variable in Javascript.
16. What is var?
17. What is let?
18. What is const?
19. What is difference between let and var?
20. What is difference between let and const?
21. What is automatic type conversion?
22. What are operators in Javascript?
23. Explain types of operators.
24. What are control flow statements?
25. What is break statement?
26. What is continue statement?
27. What is the difference between comparing variables using “==” and “===”
operator?
28. What is typeof operator?
29. What is variable hoisting?
30. What is difference between undefined and null?
31. What is output of null == undefined?
32. What are escape characters?
33. How to create array in javascript?
34. How to create three dimensional array?
35. What are the variable naming conventions in JavaScript?
36. Why you should not prefer to use global variables?

3. Functions

37. What are functions?
38. What are types of functions in Javascript?
39. What are frequently used built-in global functions?
40. What is isNaN?
41. What is parseInt?
42. What is alert?
43. What is confirm?
44. What is charAt?
45. What is indexOf?
46. What are function scopes?
47. What is strict mode?
48. What is function closure?
49. What is callback function?
50. What is setTimeout function?
51. What is setInterval function?
52. What is difference between setInterval and setTimeout functions?
53. What is encodeURI() method?
54. What is decodeURI() method?

4. Events

55. What are Events?
56. What are different events in Javascript?
57. What are event handlers?
58. What is addEventListener() method?
59. How to remove event listener from any element?
60. What are different key codes?
61. What is event bubbling?
62. Is it possible to stop event bubbling?
63. What is event capturing?
64. What is event delegation?

5. Objects

65. What is Object?
66. What are ways to create objects?
67. Which are built-in or native objects?
68. What is ‘this’ keyword?
69. Explain about String object.
70. Explain about Number object.
71. Explain about Boolean object.
72. Explain about Array object.
73. Explain about Date object.
74. Explain about Math object.
75. Explain about RegExp object.
76. What is namespace?
77. How to create namespace?
78. What is prototype in javascript?
79. What is prototypal inheritance?
80. What is difference between call() and apply()?
81. What is Promise?

6. Browser Object Model

82. What is Browser Object Model?
83. What is Window Object?
84. Explain alert method of window object.
85. Explain confirm method of window object.
86. Explain prompt method of window object.
87. How to redirect other webpage?
88. What is Navigator Object?
89. How to identify operating system of client device?
90. What is History Object?
91. How to load previous page in browser programmatically?
92. How to load next page in browser programmatically?
93. What is go method of history object?
94. What is Screen Object?
95. What is Location Object?
96. How to print a web page?

7. Document Object Model

97. What is Document Object?
98. What is DOM?
99. What are DOM nodes?
100. How to get element with id in DOM?
101. How to get element using class in DOM?
102. How to get content of any element?
103. What are DOM levels?
104. What are deferred scripts?
105. What are asynchronous scripts?
106. What is difference between attribute and property?
107. What is the difference between innerHTML & innerText?
108. What is the difference between textContent & innerText?
109. What is HTMLCollection?
110. What is NodeList?
111. What are frames?

8. Cookies

112. What is cookie?
113. How cookie helps client server HTTP communication?
114. Where are cookies stored?
115. Where are parameters of cookie?
116. Can user disable cookies?
117. How to create cookie?
118. How to read cookie?
119. How to delete cookie?
120. What is difference between local storage and session storage?

9. Form validation

121. What is form validation?
122. What is required attribute?
123. What is pattern attribute?
124. How to validate form using Javascript function?
125. How to validate email in the form?
126. How to validate field without submitting form?
127. What is .test method?
128. What is .match method?
129. How to validate Date?
130. How to allow number only in input field?
10. Error and Exception Handling
131. What is error object?
132. What are different error types in Javascript?
133. How to handle exceptions in JavaScript?
134. Explain try…catch…finally.
135. How to throw exceptions programmatically?

11. Debugging

136. What is debugging?
137. What is debugger keyword?
138. What is console object?
139. How to activate debugging in browser?
140. How to get mobile devices view of webpage in desktop browser?
141. How to deactivate breakpoint in browser?
142. How to pause script execution?
143. How to execute function line by line while debugging?
144. How to execute function without stepping into it while debugging?
145. What is code smell?

12. AJAX overview

146. What is AJAX?
147. What is difference between GET and POST?
148. What is XMLHttpRequest object?
149. How to make HTTP GET call using AJAX?
150. How to make HTTP POST call using AJAX?
151. What are HTTP status codes?

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