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React js interview questions

Express Your JS Interview Questions

1) What is Reaction JS?
2) List some of the benefits of ReactJS?
3) What are the components of Reaction JS?
4) What is JSX?
5) Define the life of reactive JS components?
6) List some of the features of React JS?
7) How to use events in ReactJS?
8) What is the flow in javascript?
9) What are React J? When to use it.
10) What are the stateless ingredients in ReactJS?
11) What is the difference between props in states and limits and reactions?
12) What are artificial events?
13) What is the difference between Doom and Virtual Doom in React JS?
14) List the advantages and disadvantages of ReactJS?
15) What are Controlled Components and Uncontrolled Components in ReactJS?
17) What do you think of React J through mixin or high order ingredients?
18) How is the flow different from the redox?
19) How is ReactJS different from Angular.
20) What is the use of the arrow function in React JS?
21) What are the things in React JS?
22) What is the purpose of the () function (render) in racket js?
Last Updated: December 06, 2019
Posted in Interview Questions,
22 questions
Express Your JS Interview Questions
Reactus is an open source JavaScript UI (user interface) library, co-authored and overseen by Facebook and Instagram and a large group of developers. It is designed to adapt your request status and allow you to write code that inputs its status and returns the virtual DOM, manipulating the DOM and handling events. Definitely a better way, which is really just a set.

Each brand wants to create an interactive UI for their mobile users as it keeps them engaged for longer and results in more conversions. In this way, brands select the best talent from the developer community and offer them attractive packages. If you are a developer willing to join the industry, here are some React.js interview questions that answer all the important elements of React Js. In this post, we've included some basic and advanced feedback JS Interview Questions.

As such, these questions are compiled on React Js with both basic and advanced questions. Preparing for your interview with these questions will put you ahead of others and help you to break the exam.

Advanced Feedback JS Interview Questions

Below is a list of the Best React JS Interview Questions and Answers

1)    What is Reaction JS?

React JS is a JavaScript based UI library built on Facebook to create interactive, state-of-the-art UI components. This is one of the popular JavaScript frameworks that is configured to handle the presentation layer for web and mobile apps.

2) List some of the benefits of ReactJS?

Benefits of reactive JS

React.js is extremely efficient: React.js creates its own virtual DOM where your components really live. This approach gives you a lot of flexibility and an amazing advantage in performance. React.js also calculates what changes need to be made to the domain. This React.js process avoids costly DOM operations and is very refreshing.
This makes it easy to write JavaScript: React.js uses a special syntax called JSX, which allows you to blend HTML with JavaScript. The user can drop a little HTML in the render function without adding wires, which is another amazing thing. React.js converts bits of HTML into functions with a special JSXTransformer.
It gives you out-of-the-box developer tools: When you begin your journey with React.js, be sure to install the regular React.js Chrome extension. This makes it easier to fix your application. After you install the extension, you will have a direct look at the virtual DOM as if you were viewing the regular DOM tree in the Elements panel. Isn't it amazing!
This is pretty good for SEO: The biggest problem with other JavaScript frameworks is that they don't look engine friendly. Although there has been some improvement in this area, search engines generally have difficulty reading heavy JavaScript applications. React.js is separate from the crowd because you can run React.js on the server, and the virtual DOM will be presented as a regular web page in the browser.
UI Test Cases: Writing UI test cases is extremely easy because the virtual DOM system is fully implemented in JS.

3) What are the components of Reaction JS?

React components let you split the UI into independent, reusable pieces, and think of each piece separately.
Conceptually, the components are similar to the JavaScript functions. They accept arbitrary inputs (called "props") and return the elements that define what should appear on the screen.

JS Components React to Biology

Each component has several "lifecycle modes" that you can override to run the code at certain times in the process. Methods that are executed before a thing happens are called correct, and the methods that are already occurring are called explicit.


These methods are called when a component is being developed and inserted into the domain:

Constructor ()
Ingredients Valmount ()
Component History ()
An update may be due to supporters or changes to the state. These methods are called when these components are being recreated

Ingredients Wheel Recipes ()
shouldCompenderUpdate ()
Component Will Opt ()
Component Dead Update ()
This method is called when removing a component from the DOM:

Components against ()
Other APIs
Each component also provides some other APIs.

Set state ()
Strength update ()
Class Properties
already decided
Display name
Example properties

6) List some of the features of React JS?

Today, of course, React is one of the best JavaScript UI frameworks. It comes with many features that help programmers easily create beautiful applications, we've listed some of them below.
This is the adaptation
Free and open source
Decoration from ES7
Server Side Communication
Irrelevant functions and generators
Flux Library
Assignment construction
Jsx utility
Also, read the interview response questions

7) How to use events in ReactJS?

Using events is equivalent to handling events on Js DOM elements.
The name of the event is React js always in the camel case.
With JSX you pass an event handler instead of a string.
To illustrate:

// in the HTML
<Button OnLink = "Active Account ()">
Activated account
// in response
Click <button = {active account}>
Activated account
The other difference is that in React js you cannot return false to prevent the default behavior in the react function. You should explicitly call Prevention Defaults. 

8) What is the flow in javascript?

Flux is an application architecture for creating layers of data in JavaScript applications. It was designed alongside the React View library on Facebook. Flux is not a framework or library. It's just a new type of architecture that caters to the concept of reactive and unidirectional data flows.

9) What are React J? When to use it.

React is used to store the reference element or component reference which causes a Ranger () configuration function. Reefs should be avoided in most cases, however, they can be useful when we need a dome measure or add methods to the components.
Reefs can be used in the following cases

Focus, text selection, or media playback management.
Animating dynamic animations.
Integrates with third party DOM libraries.
10) What are the stateless ingredients in ReactJS?
Non-state components are components that have no state. When something is stateless, it calculates its internal state, but it never changes it directly. State-class ingredients do not require any classes and keywords. You can create state-equipped components using simple functions or the S6 arrow function. The following is an example of a Bay Area component in reaction.
// in S6
Cont pane = (support) =>
s props.children}

// in S5
const username = ({username}) =>
Login user is: {username}

11) What is the difference between props in states and limits and reactions?

Properties are shorthand for properties. This is very similar to an argument in a pure JavaScript function. The component pointers go through the parent component that asks for the component. During the life span of an ingredient, they should not be considered for change. All support in the React process may be available as well.
Import from 'React';
Welcome to the class responds. Components {
Render () nder
Return <h1> hello {this.prop.name} </h1>;
Fixed element =;
The State is used to create dynamic and interactive components in a React. State is the heart of the process that brings it alive and determines how the component performs and behaves.

// Simple example of a state
Import from 'React';
The class button expands the response. Components {
Constructor () {
Super ();
This.state = {
Count: 0,

update () (
this.setState ((prevState, props) => {
Return {count: prevState.count + 1

Render () nder
Back (<button)
onClick = {() => this.updateCount ()}
{this.state.count} times clicked

Export default buttons

12) What are artificial events?

Artificial Event is a cross browser wrapper around the browser native. All of you in response

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