Technical interview questions and answers are extremely important for JavaScript Interviews because JavaScript powers most modern web applications. Companies evaluate your understanding of functions, scope, closures, events, DOM manipulation, ES6 features, promises, async/await, and real-time coding skills. JavaScript is one of the most commonly tested subjects in frontend developer interviews, full-stack roles, and placement assessments. Companies like TCS, Infosys, Wipro, Cognizant, and Accenture frequently include JavaScript questions in their technical rounds. This guide covers the most frequently asked JavaScript interview questions with detailed explanations to help freshers and job seekers prepare effectively. Learning these questions will give you confidence during coding tests, practical tasks, and web development interviews.
Frontend developers should enhance their skills by mastering CSS styling techniques and HTML structure fundamentals
Showing 10 of 78 questions
1. what is the differene between java and java script?
Java Script is object based language it is used for front end validations
java is object oriented language object oriented language supports OOP's Object based not suppoted inheritence.
3. 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);
4. What does isNaN function do ?
Return true if the argument is not a number.
5. What is negative infinity?
Its a number in JavaScript, derived by dividing negative number by zero.
6. What boolean operators does JavaScript support?
&&, || and !
7. What does "1"+2+4 evaluate to?
Since 1 is a string, everything is a string, so the result is 124.
8. What looping structures are there in JavaScript?