Expert Developer JavaScript Interview Preparation Guide
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Expert Developer JavaScript Frequently Asked Questions by expert members with experience in Expert JavaScript Developer. These questions and answers will help you strengthen your technical skills, prepare for the new job test and quickly revise the concepts

150 Expert JavaScript Developer Questions and Answers:

1 :: What is the use of isNaN function?

isNan function returns true if the argument is not a number otherwise it is false.

2 :: Which company developed JavaScript?

Netscape is the software company who developed JavaScript.

3 :: What is a prompt box in JavaScript?

A prompt box is a box which allows the user to enter input by providing a text box. Label and box will be provided to enter the text or number.

4 :: Which symbol is used for comments in Javascript?

// for Single line comments and

/* Multi




5 :: What is === operator in JavaScript?

=== is called as strict equality operator which returns true when the two operands are having the same value without any type conversion.

6 :: What would be the result of 3+2+"7″?

Since 3 and 2 are integers, they will be added numerically. And since 7 is a string, its concatenation will be done. So the result would be 57.

7 :: What is an undefined value in JavaScript?

Undefined value means the

► Variable used in the code doesn't exist
► Variable is not assigned to any value
► Property doesn't exist

8 :: What are escape characters?

Escape characters (Backslash) is used when working with special characters like single quotes, double quotes, apostrophes and ampersands. Place backslash before the characters to make it display.


document.write "I m a "good" boy"

document.write "I m a "good" boy"

9 :: What is the use of type of operator?

'Typeof' is an operator which is used to return a string description of the type of a variable.

10 :: Tell me what is JavaScript?

JavaScript is a client-side scripting language that can be inserted into HTML pages and is understood by web browsers.