Interview Questions of React JS

I have given few Interviews in React JS and this blog is based on that experience. Usually for React JS interviews it is expected you have a deep understanding about JavaScript and other few libraries used with React JS like Redux, Thunk and Redux Saga. In 2 interviews I was asked questions on HTML5 and CSS3 even though the profile was React JS Developer.

If you are giving interview in product based company there are usually 2 technical round. In second technical round you have been asked to make a mini application in React JS like a countdown timer.

Q1. What is Virtual DOM in React JS?
Q2. What are the major advantages of React JS over Angular JS?
Q3. What are the limitations of React JS ?
Q4. How will you decide when to use React JS?
Q5. What is component in React JS?
Q6. Explain how will you pass property from Child Component to Parent Component?
Q7. Explain component lifecycle?
Q8. What is JSX?
Q9. Differentiate Props vs State?
Q10. Explain render method and its use?
Q11. What is events in React JS and explain its types?
Q12. What is hooks?
Q13. What is fragments?
Q14. What is HOC in React JS and its use?
Q15. Explain Redux and when it is used?
Q16. What is Redux Thunk and Redux Saga? When do we use thunk and when do we use saga?

Key Terms in React JS

Key Terms in React JS

1) ECMAScript

-ECMAScript is a scripting-language standardization by ECMA International. React without ECMAScript 6 would be a plain JavaScript component.

2) Component 

-The entire application of React is modelled as a set of independent, reusable and isolated pieces called components.
- There are two ways the components receive data through :- Props or State

3) Properties / Props

- It is a way of passing data from parent component to child component.
- Props are immutable

4) State 

- State is managed within the component.
- It is used to store data about the component which can change over time. Thus, state makes a component dynamic and interactive

5) JSX (JavaScript Extension)

-  JSX allows us to include ‘HTML’ along with ‘JavaScript’
- React doesn’t require it but it is helpful in working with UI inside the JavaScript code.
- It is faster, easier and type safe.

6) Webpack

- Webpack is a popular module bundling system which generates a build file joining all the dependencies.
- It checks for import and require statement in files and builds a dependency graph.

7) Babel

- Babel is a JavaScript compiler that includes the ability to compile JSX into regular JavaScript.
- This is used because not all web browsers can render JSX along with ES6 directly.

Here is my video on Key Terms in React JS