100 TOP JavaScript Interview Questions and Answers pdf

Most Frequently Asked 100 TOP Javascript Interview Questions and Answers for beginners and experienced pdf free download
1.  Difference between window.onload and onDocumentReady?
2.  What is the difference between == and === ?
3.  What does “1?+2+4 evaluate to? What about 5 + 4 + “3??
4.  What is the difference between undefined value and null value?
5.  How do you change the style/class on any element?
6.  What are Javascript closures?When would you use them?
7.  What is unobtrusive javascript? How to add behavior to an element using javascript?
8.  What is Javascript namespacing? How and where is it used?
9.  What datatypes are supported in Javascript?
10. What is the difference between innerHTML and append() in JavaScript?
11. When would you use var in your declaration and when you wouldn’t?
12. What does the attribute defer/async do when added to the script tag?
13. What is the difference between == and ===? Which one would you use?
14. How would you check if a variable is null/undefined?
15. How do you check if a variable is an object
16. Discuss  scoping in JavaScript.?
17. Explain hoisting in JavaScript.?
18. Explain prototypal/differential inheritance.?
19. What is Strict Mode in JavaScript.?
20. What are JavaScript types? 
21. How do you convert numbers between different bases in JavaScript?
22. What does "1"+2+3 evaluate to?
23. How about 3+5+"8"?
24. How do you submit a form using Javascript? 
25. How do you assign object properties?
26. What’s a way to append a value to an array?
27. What does isNaN function do? 
28. What’s relationship between JavaScript and ECMAScript?
29. How to read and write a file using javascript? 
30. How do you convert numbers between different bases in JavaScript? 
31. What is negative infinity? 
32. How to set a HTML document's background color? 
33. What Boolean operators does JavaScript support?
34. How to get the contents of an input box using Javascript? 
35. How to determine the state of a checkbox using Javascript? 
36. How to set the focus in an element using Javascript? 
37. How to access an external javascript file that is stored externally and not embedded? 
38. What is the difference between an alert box and a confirmation box? 
39. What is a prompt box? 
40. Can javascript code be broken in different lines? 
41. What looping structures are there in JavaScript?
42. How do you create a new object in JavaScript?
43. What is this keyword?
44. What is the difference between SessionState and ViewState? 
45. What looping structures are there in JavaScript? 
46. To put a "close window" link on a page ? 
47. How to hide javascript code from old browsers that dont run it? 
48. How to comment javascript code? 
49. Name the numeric constants representing max,min values 
50. What does javascript null mean? 
51. How do you create a new object in JavaScript? 
52. How do you assign object properties? 
53. What is other equivalent option of document.getElementById() when you are working with Ajax?
54. To set all checkboxes to true using JavaScript? 
55. What does undefined value mean in javascript? 
56. What is the difference between undefined value and null value? 
57. What is variable typing in javascript? 
58. Does javascript have the concept level scope? 
59. What are undefined and undeclared variables? 
60. What is === operator ? 
61. How to disable an HTML object ?
62. How to create a popup warning box?
63. How to create a confirmation box? 
64. How to create an input box? 
65. How to force a page to go to another page using JavaScript ? 
66. What's Math Constants and Functions using JavaScript? 
67. What does the delete operator do? 
68. How to get value from a textbox?
69. How to get value from dropdown (select) control?
70. How do you write an event emitter base class that allows you to add event listeners?
71. What is the concept of “functions as objects” and how does this affect variable scope?
72. What is the difference between .call() and .apply()?
73. Can you explain how inheritance works in JavaScript?
74. What is event bubbling in the DOM?
75. How to get value from a textbox?
76. How to get value from dropdown (select) control.?
77. How to get value from RadioButtonList control?
78. How to get CheckBox status whether it is checked or not?
79. How to toggle display an HTML element?
80. What is undefined value means in JavaScript?
81. Is it possible make a call to server side event of any button using javascript?
82. How can you set position of the page (Top and Left) to 0 using Javascript in one line code?
83. What is the result of below given line of code in Java Script? 5+4+'7'
84. Name the DataTypes of JavaScript?
85. Write a way by which you can do something on the close of the window ?
86. How to create an Object in JavaScript ?
87. Basic methods for opening a PopUp window using Javascript?
88. What is JSON?
89. How can you detect the Client Operating System using Javascript?
90. What is the data type of variables in JavaScript?
91. What is negative infinity?
92. if 2 methods have same name and same number of parameters, which one will be executed first?
93. Difference between undefined and undeclared variables.
94. Difference Json Arrary Vs Json Object ?
95. What is the difference of "setTimeout" function and setInterval functions in Javascript
96. What is the difference between the below two statements:- (1) var myname = "Akiii"; (2) myname = "Akiii";
97. What data type javascript supports?
98. What is isNaN in javascript?
99. How will you create new object in javascript?
100. How do you create array in javascript?

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