JavaScript Interview Questions and Answers

Ques 1. What are JavaScript data types?

• Number
• String
• Boolean
• Function
• Object
• Null
• Undefined.

Ques 2. How do you convert numbers between different bases in JavaScript?

Use the parseInt() function, that takes a string as the first parameter, and the base as a second parameter. So to convert hexadecimal 3F to decimal, use parseInt ("3F", 16);

Ques 3. What does isNaN function do?

Return true if the argument is not a number.

Ques 4. What looping structures are there in JavaScript?

• for
• while
• do-while
• foreach

Ques 5. What boolean operators does JavaScript support?

• &&
• ||
• !