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Utilizing React Context Hook – Java Code Geeks

Welcome readers, on this tutorial, we’ll perceive the best way to use the Context Hook in a React-js utility.

1. Introduction

React is a versatile javascript library liable for constructing reusable UI elements. It’s an open-source component-based frontend library accountable just for the view a part of an utility and works in a digital doc object mannequin. However earlier than that permit us check out the variations between angular and react –

Angular React
Full framework Library
Object-oriented programming Extension to the javascript library and its inner structure relies on jsx
Based mostly on the mannequin view controller and actual doc object mannequin Based mostly on the digital doc object mannequin

1.1 Use Context hook in React-js

Hooks in React-js are the capabilities which can be hooked into react-js state and lifecycle options from perform elements. The useContext(…) permits the elements to entry international information and re-render when that international information is modified. It helps to resolve the drilling downside when we’ve got to go props from mother and father to youngsters elements. It helps to take away the advanced nesting.

  • Props drilling in React-js is an issue the place information is handed from one part via a number of a number of interdependent elements till we get to the part the place the info is required

1.2 Organising dependencies

To play with React allow us to arrange among the required dependencies.

1.2.1 Organising Node.js

To arrange Node.js on home windows you have to to obtain the installer from this hyperlink. Click on on the installer (additionally embrace the NPM package deal supervisor) in your platform and run the installer to start out with the Node.js setup wizard. Comply with the wizard steps and click on on End when it’s finished. If every little thing goes nicely you’ll be able to navigate to the command immediate to confirm if the set up was profitable as proven in Fig. 1.

Fig. 1: Verifying node and npm installation
Fig. 1: Verifying node and npm set up

1.2.2 Organising React-js challenge

As soon as the Nodejs setup is profitable we’ll use the beneath command to put in the react library and arrange the challenge. Do word that the npx package deal is obtainable with the npm 5.2 model and above.

Create challenge construction

$ npx create-react-app usecontext-app

The above command will take a while to put in the react library and create a brand new challenge named – usecontext-app as proven beneath.

Fig. 2: Project structure
Fig. 2: Venture construction

2. Utilizing React Context Hook

To arrange the appliance, we might want to navigate to a path the place our challenge will reside and I can be utilizing Visible Studio Code as my most well-liked IDE.

2.1 Organising the react code

To know a sensible implementation allow us to undergo some hands-on workout routines.

2.1.1 Creating elements

Create a folder named elements within the src folder. Creating ChildA part

Add the next code to the ChildA.js file. We’ll use the useContext(..) hook to retrieve the info from the titleContext context. The context can be handed from the App.js file.


import React, { useContext } from "react";
import { titleContext } from "../App";
import ChildB from "./ChildB";

const ChildA = () => {
  // retrieved from app.js
  const title = useContext(titleContext);

  return (

export default ChildA; Creating ChildB part

Add the next code to the ChildB.js file. We’ll use the useContext(..) hook to retrieve the info from the genreContext and nameContext context. The context can be handed from the App.js file.


import React, { useContext } from "react";
import { genreContext, nameContext } from "../App";

const ChildB = () => {
  // retrieved from app.js
  const web site = useContext(nameContext);
  const websiteGenre = useContext(genreContext);

  return (
        {web site} is of {websiteGenre} class

export default ChildB;

2.1.2 Creating implementation file

Within the App.js part we’ll name the kid part and export the created contexts. We’ll use the createContext(…) methodology to create a context occasion and Supplier on the context occasion to offer the context to the kid elements, regardless of how deep they’re within the utility. To set the worth of the context we use the worth prop out there on the supplier.


import { createContext } from "react";
import "./App.css";
import ChildA from "./elements/ChildA";

// what's the useContext hook?
// create, supplier, useContext
// permits the part to entry some international information and re-render when that international information is modified.
// solves props drilling downside after we go down props from mother and father to youngsters.

// the best way to use it?
const titleContext = createContext();
const nameContext = createContext();
const genreContext = createContext();

perform App() {
  const title = "useContext hook in reactjs";
  const identify = "javacodegeeks";
  const style = "studying";

  return (
    <div className="App">
      <titleContext.Supplier worth={title}>
        <nameContext.Supplier worth={identify}>
          <genreContext.Supplier worth={style}>

export default App;
export { titleContext, nameContext, genreContext };

3. Run the setup

To run the appliance navigate to the challenge listing and enter the next command as proven beneath within the terminal.

Run command

$ npm run begin

The appliance can be began on the default port. In case the appliance doesn’t get began on the default port you’ll be able to change the port quantity as per your requirement. I’ve modified the default port to 2000.

Fig. 3: Application run
Fig. 3: Utility run

4. Demo

The appliance can be began within the default browser as proven beneath and a welcome message can be proven.

Fig. 4: Default home page
Fig. 4: Default residence web page

That’s all for this tutorial and I hope the article served you with no matter you have been in search of. Glad Studying and don’t forget to share!

5. Abstract

On this tutorial, we created a react utility and understood the Context Hook in React-js. You’ll be able to obtain the supply code from the Downloads part.

6. Obtain the Venture

This was a tutorial to know the useContext() hook in a react utility.



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