JavaScript / ReactJS Interview Questions

Preparing for a JavaScript or ReactJS interview can be daunting, but studying some common interview questions can help you feel more confident and prepared. Below are some frequently asked interview questions for JavaScript and ReactJS.

JavaScript Interview Questions:

1. What is JavaScript?
2. What are the different data types in JavaScript?
3. What is the difference between let and var in JavaScript?
4. What are closure in JavaScript?
5. Explain prototypal inheritance in JavaScript.
6. What is the use of the ‘this’ keyword in JavaScript?
7. How do you handle errors in JavaScript?
8. What is event delegation in JavaScript?

ReactJS Interview Questions:

1. What is ReactJS?
2. What are the key features of ReactJS?
3. What is JSX in ReactJS?
4. What is the virtual DOM in ReactJS?
5. How does state differ from props in ReactJS?
6. What are controlled components in ReactJS?
7. What is the significance of key attribute in ReactJS?
8. How do you optimize performance in ReactJS?

These are just a few examples of the types of questions that you may encounter in a JavaScript or ReactJS interview. It’s important to not only know the answers to these questions, but also to be able to explain your thought process and problem-solving skills. Good luck!