Top 5 Interview Questions For Junior React Developers in 2022.

It's becoming increasingly difficult to choose the correct technology for a new app or website. React is one of the most rapidly expanding Javascript frameworks. There has been a steady rise in demand for React certification as JavaScript technologies have established themselves in the industry. React is a clear winner for front-end developers all around the world because of its short learning curve, reusable components, and clean abstraction. To help you with your interview preparation, we've compiled a list of some of the most common React interview questions and answers.

Let's take a look at five of the most common React Interview questions:

1. What are React's features?

JSX: JSX is a JavaScript syntactic extension. It's a term used in React to define the desired appearance of the user interface. It is possible to write HTML structures in the same file as JavaScript code thanks to the JSX language extension.
Components: There are many components in a single React application, so it's important to know what they are and how they work together. It separates the user interface into components that may be reused and processed independently of one another.
Virtual DOM: In React, the virtual DOM is a lightweight replica of the actual DOM that is stored in memory. Rather to updating every item in the DOM, the virtual DOM simply updates one object at a time.
One-way data-binding: In React, the one- way data binding ensures that everything is modular and quick. A React app's unidirectional data flow necessitates nesting child components inside parent components.
High Performance: In order to keep things running smoothly, React only updates the parts that have changed. As a consequence, web applications run substantially more quickly.

2. What are the major differences between Real DOM and Virtual DOM? (Real Dom vs Virtual DOM)

Real DOM	Virtual DOM
It's taking a while to update.	It's more responsive in terms of updating.
It is possible to make HTML changes straight from the command line.	It is not possible to change HTML directly.
If an element's data changes, a new DOM is created.	If an element changes, the JSX is updated.
In order to manipulate the DOM, the process is quite time-consuming.	It's fairly simple to work with the DOM.
Memory is being squandered.	Memory is not wasted.

3. How is React's ES6 syntax different from that of ES5 in terms of syntax?

When comparing ES5 to ES6, the following features of the syntax have been updated:

importing vs. requiring
export vs exports
component and function
props
state

Import vs. Requiring

ES5 var React = require('react');

ES6 import React from 'react';

Export vs Exports

ES5 module.exports = Component;

ES6 export default Component;

Component and Function

// ES5 Component
var MyComponent = React.createClass({
  render: function () {
    return <h3>Hello Edureka!</h3>;
  },
})
// ES6 Function
class MyComponent extends React.Component {
  render() {
    return <h3>Hello Edureka!</h3>
  }
}

Props

// ES5
var App = React.createClass({
  propTypes: { name: React.PropTypes.string },
  render: function () {
    return <h3>Hello, {this.props.name}!</h3>
  },
})
// ES6
class App extends React.Component {
  render() {
    return <h3>Hello, {this.props.name}!</h3>
  }
}

State

// ES5
var App = React.createClass({
  getInitialState: function () {
    return { name: 'world' }
  },
  render: function () {
    return <h3>Hello, {this.state.name}!</h3>
  },
})
// ES6
class App extends React.Component {
  constructor() {
    super()
    this.state = { name: 'world' }
  }
  render() {
    return <h3>Hello, {this.state.name}!</h3>
  }
}

4. List some of the most important benefits of using React in your essay.

React has a number of significant benefits, including the following:

It improves the speed and responsiveness of the program.
It is suitable for both the client and the server.
The readability of code has improved as a result of JSX
With React, additional frameworks like Meteor and Angular may be easily integrated.
Writing UI test cases becomes a breeze with the help of React.

5. What are the reasons why browsers don't support JSX?

Only JavaScript objects are supported by browsers, but JSX is not one of them. For this reason, JSX files must first be converted into JavaScript objects like Babel before being sent to the browser.