JavaScript Hello World Sample - React

React is a JavaScript library meant explicitly for creating interactive UIs. Follow this guide to learn how to implement Dynamsoft Barcode Reader JavaScript SDK (hereafter called “the library”) into a React application. Note that in this sample we will use TypeScript and define components as classes. Also, there is another sample read-video-react-hooks showing using Hooks in React.

Official Sample

Hello World in React - Source Code

Preparation

Make sure you have node installed. node 14.21.3 and react 18.2.0 used in the example below.

Create the sample project

Create a Bootstrapped Raw React Application with TypeScript

npx create-react-app read-video-react --template typescript

CD to the root directory of the application and install the library

cd read-video-react
npm install dynamsoft-javascript-barcode

Start to implement

Add a file “dbr.ts” under “/src/” to configure the library

import { BarcodeReader } from 'dynamsoft-javascript-barcode';
BarcodeReader.license = 'DLS2eyJvcmdhbml6YXRpb25JRCI6IjIwMDAwMSJ9';
BarcodeReader.engineResourcePath = "https://cdn.jsdelivr.net/npm/dynamsoft-javascript-barcode@9.6.42/dist/";

Note:

license specify a license key to use the library. You can visit https://www.dynamsoft.com/customer/license/trialLicense?utm_source=sample&product=dbr&package=js to get your own trial license good for 30 days.

engineResourcePath tells the library where to get the necessary resources at runtime.

Build directory structure

Create a directory “components” under “/src/”, and then create another three directories “HelloWorld”, “VideoDecode” and “ImgDecode” under “/src/components/”.

Create and edit the `VideoDecode` component

Create VideoDecode.tsx and VideoDecode.css under “/src/components/VideoDecode/”. The VideoDecode component uses BarcodeScanner class of the library to decode barcodes via camera.
In VideoDecode.tsx, add code for initializing and destroying the BarcodeScanner instance.

import { BarcodeScanner } from "dynamsoft-javascript-barcode";
import React from 'react';
import './VideoDecode.css'

class VideoDecode extends React.Component {
    pScanner: Promise<BarcodeScanner>|null = null;
    elRef: React.RefObject<HTMLDivElement> = React.createRef();
    async componentDidMount() {
        try {
            const scanner = await (this.pScanner = BarcodeScanner.createInstance());
            // Should judge if scanner is destroyed after 'await', as in development React runs setup and cleanup one extra time before the actual setup in Strict Mode. 
            if(scanner.isContextDestroyed()) return;
            await scanner.setUIElement(this.elRef.current!);
            // Should judge if scanner is destroyed after 'await', as in development React runs setup and cleanup one extra time before the actual setup in Strict Mode. 
            if(scanner.isContextDestroyed()) return;
            scanner.onFrameRead = results => {
                for (let result of results) {
                    console.log(result.barcodeText);
                }
            };
            scanner.onUniqueRead = (txt, result) => {
                alert(txt);
            }
            await scanner.open();
        } catch (ex: any) {
            if (ex.message.indexOf("network connection error")) {
                let customMsg = "Failed to connect to Dynamsoft License Server: network connection error. Check your Internet connection or contact Dynamsoft Support (support@dynamsoft.com) to acquire an offline license.";
                console.log(customMsg);
                alert(customMsg);
            }
            throw ex;
        }
    }
    async componentWillUnmount() {
        if (this.pScanner) {
            (await this.pScanner).destroyContext();
            console.log('BarcodeScanner Component Unmount');
        }
    }
    shouldComponentUpdate() {
        // Never update UI after mount, dbrjs sdk use native way to bind event, update will remove it.
        return false;
    }
    render() {
        return (
            <div ref={this.elRef} className="component-barcode-scanner">
                <svg className="dce-bg-loading" viewBox="0 0 1792 1792"><path d="M1760 896q0 176-68.5 336t-184 275.5-275.5 184-336 68.5-336-68.5-275.5-184-184-275.5-68.5-336q0-213 97-398.5t265-305.5 374-151v228q-221 45-366.5 221t-145.5 406q0 130 51 248.5t136.5 204 204 136.5 248.5 51 248.5-51 204-136.5 136.5-204 51-248.5q0-230-145.5-406t-366.5-221v-228q206 31 374 151t265 305.5 97 398.5z"></path></svg>
                <svg className="dce-bg-camera" viewBox="0 0 2048 1792"><path d="M1024 672q119 0 203.5 84.5t84.5 203.5-84.5 203.5-203.5 84.5-203.5-84.5-84.5-203.5 84.5-203.5 203.5-84.5zm704-416q106 0 181 75t75 181v896q0 106-75 181t-181 75h-1408q-106 0-181-75t-75-181v-896q0-106 75-181t181-75h224l51-136q19-49 69.5-84.5t103.5-35.5h512q53 0 103.5 35.5t69.5 84.5l51 136h224zm-704 1152q185 0 316.5-131.5t131.5-316.5-131.5-316.5-316.5-131.5-316.5 131.5-131.5 316.5 131.5 316.5 316.5 131.5z"></path></svg>
                <div className="dce-video-container"></div>
                <div className="dce-scanarea">
                    <div className="dce-scanlight"></div>
                </div>
                <div className="div-select-container">
                    <select className="dce-sel-camera"></select>
                    <select className="dce-sel-resolution"></select>
                </div>
                <div className="dbr-msg-poweredby"><svg viewBox="0 0 94 17"><g><path d="M0.9,14V4.3h2.3c0.6,0,1,0.1,1.4,0.3c0.3,0.2,0.6,0.5,0.7,0.9s0.2,0.8,0.2,1.4c0,0.5-0.1,0.9-0.2,1.3 C5.1,8.5,4.9,8.8,4.5,9.1C4.2,9.3,3.7,9.4,3.2,9.4H1.8V14H0.9z M1.8,8.7h1.2c0.4,0,0.7-0.1,1-0.2S4.3,8.2,4.4,8 c0.1-0.3,0.2-0.6,0.2-1.1c0-0.5,0-0.9-0.1-1.2C4.3,5.4,4.2,5.2,3.9,5.1S3.4,5,2.9,5H1.8V8.7z" /><path d="M8.1,14.1c-0.5,0-0.8-0.1-1.1-0.3s-0.5-0.5-0.6-0.9s-0.2-0.9-0.2-1.4V9.6c0-0.6,0.1-1,0.2-1.4 C6.5,7.8,6.7,7.5,7,7.3S7.6,7,8.1,7C8.6,7,9,7.1,9.2,7.3s0.5,0.5,0.6,0.9C9.9,8.5,9.9,9,9.9,9.6v1.9c0,0.6-0.1,1-0.2,1.4 c-0.1,0.4-0.3,0.7-0.6,0.9S8.6,14.1,8.1,14.1z M8.1,13.4c0.3,0,0.5-0.1,0.7-0.2C8.9,13,9,12.8,9,12.5c0-0.3,0-0.6,0-1v-2 c0-0.4,0-0.7,0-1C9,8.2,8.9,8,8.8,7.9C8.6,7.7,8.4,7.6,8.1,7.6c-0.3,0-0.5,0.1-0.7,0.2C7.3,8,7.2,8.2,7.2,8.5c0,0.3-0.1,0.6-0.1,1 v2c0,0.4,0,0.7,0.1,1c0,0.3,0.1,0.5,0.3,0.7C7.6,13.4,7.8,13.4,8.1,13.4z" /><path d="M12,14l-1.1-6.9h0.7l0.9,5.8l1.1-5.8h0.8l1.1,5.8l0.8-5.8H17L15.9,14H15l-1.1-5.6L12.8,14H12z" /><path d="M19.8,14.1c-0.4,0-0.8-0.1-1.1-0.3s-0.5-0.5-0.6-0.9c-0.1-0.4-0.2-0.9-0.2-1.6V9.6c0-0.7,0.1-1.2,0.2-1.6 c0.1-0.4,0.3-0.7,0.6-0.8C19,7,19.3,7,19.8,7c0.5,0,0.9,0.1,1.1,0.3c0.3,0.2,0.4,0.5,0.5,0.9c0.1,0.4,0.1,1,0.1,1.6v0.6h-2.8v1.2 c0,0.4,0,0.8,0.1,1.1c0.1,0.3,0.2,0.4,0.3,0.6s0.3,0.2,0.6,0.2c0.2,0,0.3,0,0.5-0.1c0.1-0.1,0.3-0.2,0.3-0.4s0.1-0.5,0.1-0.8v-0.5 h0.9V12c0,0.6-0.1,1.1-0.4,1.5S20.4,14.1,19.8,14.1z M18.8,9.9h1.9V9.4c0-0.4,0-0.7-0.1-0.9c0-0.3-0.1-0.5-0.3-0.6S20,7.6,19.8,7.6 c-0.2,0-0.4,0.1-0.6,0.2c-0.1,0.1-0.3,0.3-0.3,0.6c-0.1,0.3-0.1,0.7-0.1,1.1V9.9z" /><path d="M22.8,14V7.1h0.9V8c0.2-0.4,0.5-0.6,0.8-0.8C24.8,7.1,25,7,25.3,7c0,0,0,0,0.1,0s0.1,0,0.1,0v0.9 c-0.1,0-0.1,0-0.2-0.1c-0.1,0-0.2,0-0.2,0c-0.3,0-0.5,0.1-0.7,0.2c-0.2,0.1-0.4,0.3-0.6,0.6V14H22.8z" /><path d="M28,14.1c-0.4,0-0.8-0.1-1.1-0.3s-0.5-0.5-0.6-0.9c-0.1-0.4-0.2-0.9-0.2-1.6V9.6c0-0.7,0.1-1.2,0.2-1.6 c0.1-0.4,0.3-0.7,0.6-0.8C27.3,7,27.6,7,28,7c0.5,0,0.9,0.1,1.1,0.3c0.3,0.2,0.4,0.5,0.5,0.9c0.1,0.4,0.1,1,0.1,1.6v0.6H27v1.2 c0,0.4,0,0.8,0.1,1.1c0.1,0.3,0.2,0.4,0.3,0.6s0.3,0.2,0.6,0.2c0.2,0,0.3,0,0.5-0.1c0.1-0.1,0.3-0.2,0.3-0.4s0.1-0.5,0.1-0.8v-0.5 h0.9V12c0,0.6-0.1,1.1-0.4,1.5S28.7,14.1,28,14.1z M27,9.9H29V9.4c0-0.4,0-0.7-0.1-0.9c0-0.3-0.1-0.5-0.3-0.6S28.3,7.6,28,7.6 c-0.2,0-0.4,0.1-0.6,0.2c-0.1,0.1-0.3,0.3-0.3,0.6C27.1,8.6,27,9,27,9.5V9.9z" />
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                </div>
            </div>
        );
    }
}

export default VideoDecode;

Note:
The html code in render() and the following code builds the UI for the library.
await scanner.setUIElement(this.elRef.current!);
The component should never update (check the code for shouldComponentUpdate()) so that events bound to the UI stay valid.

Define the style of the element in VideoDecode.css

.component-barcode-scanner{width:100%;height:100%;/* min-width:640px; */min-height:480px;background:#eee;position:relative;resize:both;}
.dce-bg-loading{display:none;animation:1s linear infinite dce-rotate;width:40%;height:40%;position:absolute;margin:auto;left:0;top:0;right:0;bottom:0;fill:#aaa;}
.dce-bg-camera{display:none;width:40%;height:40%;position:absolute;margin:auto;left:0;top:0;right:0;bottom:0;fill:#aaa;}
.dce-video-container{position:absolute;left:0;top:0;width:100%;height:100%;}
.dce-scanarea{width:100%;height:100%;position:absolute;left:0;top:0;}
.dce-scanlight{display:none;width:100%;height:3%;position:absolute;animation:3s infinite dce-scanlight;border-radius:50%;box-shadow:0px 0px 2vw 1px #00e5ff;background:#fff;}
.div-select-container{position:absolute;left:0;top:0;}
.dce-sel-camera{display:block;}
.dce-sel-resolution{display:block;margin-top:5px;}
.dbr-msg-poweredby{position:absolute;left:50%;bottom:10%;transform:translateX(-50%);}
.dbr-msg-poweredby svg {height:max(3vmin,17px);fill:#FFFFFF;}
@keyframes dce-rotate{from{transform:rotate(0turn);}to{transform:rotate(1turn);}}
@keyframes dce-scanlight{from{top:0;}to{top:97%;}}

Create and edit the `ImgDecode` component

Create ImgDecode.tsx and ImgDecode.css under “/src/components/ImgDecode/”. The ImgDecode component uses BarcodeReader class of the library to help decode barcodes in an image.
In ImgDecode.tsx, add code for initializing and destroying the BarcodeReader instance.

import React, { ChangeEvent, Component } from 'react'
import { BarcodeReader } from "dynamsoft-javascript-barcode";
import './ImgDecode.css'

export default class ImgDecode extends Component {
  pReader: Promise<BarcodeReader> = BarcodeReader.createInstance();

  decodeImg = async (e: ChangeEvent<HTMLInputElement>) => {
    try {
      const reader = await this.pReader;
      let results = await reader.decode(e.target.files![0]);
      for (let result of results) {
        alert(result.barcodeText);
      }
      if (!results.length) { alert('No barcode found'); }
    } catch (ex: any) {
      if (ex.message.indexOf("network connection error")) {
        let customMsg = "Failed to connect to Dynamsoft License Server: network connection error. Check your Internet connection or contact Dynamsoft Support (support@dynamsoft.com) to acquire an offline license.";
        console.log(customMsg);
        alert(customMsg);
      }
      throw ex;
    }
    e.target.value = '';
  }

  async componentWillUnmount() {
    if (this.pReader) {
      (await this.pReader).destroyContext();
      console.log('ImgDecode Component Unmount');
    }
  }

  render() {
    return (
      <div className="ImgDecode"><input type="file" onChange={this.decodeImg} /></div>
    )
  }
}

Define the style of the element in ImgDecode.css

.ImgDecode {
  display: flex;
  justify-content: center;
  align-items: center;
  border: 1px solid black
}

Create and edit the HelloWorld component

Create HelloWorld.tsx and HelloWorld.css under “/src/components/HelloWorld/”. The HelloWorld component offers buttons to switch components between VideoDecode and ImgDecode;
Add following code to HelloWorld.tsx.

import './HelloWorld.css';
import reactLogo from '../../logo.svg';
import "../../dbr"; // import side effects. The license, engineResourcePath, so on.
import { BarcodeReader } from "dynamsoft-javascript-barcode";
import React from 'react';
import VideoDecode from '../VideoDecode/VideoDecode';
import ImgDecode from '../ImgDecode/ImgDecode';

interface isState {
    bShowScanner: boolean,
    bShowImgDecode: boolean
}

class HelloWorld extends React.Component<any, isState> {
    state = {
        bShowScanner: true,
        bShowImgDecode: false
    };
    
    async componentDidMount() {
        try {
            await BarcodeReader.loadWasm();
        } catch (ex: any) {
            if (ex.message.indexOf("network connection error")) {
                let customMsg = "Failed to connect to Dynamsoft License Server: network connection error. Check your Internet connection or contact Dynamsoft Support (support@dynamsoft.com) to acquire an offline license.";
                console.log(customMsg);
                alert(customMsg);
            }
            throw ex;
        }
    }

    showScanner = () => {
        this.setState({
            bShowScanner: true,
            bShowImgDecode: false
        });
    }

    showImgDecode = () => {
        this.setState({
            bShowScanner: false,
            bShowImgDecode: true
        });
    }

    render() {
        return (
            <div className="helloWorld">
                <h1>Hello World for React<img src={reactLogo} className="App-logo" alt="logo" /></h1>
                <div>
                    <button style= onClick={this.showScanner}>Video Decode</button>
                    <button style= onClick={this.showImgDecode}>Image Decode</button>
                </div>
                <div className="container">
                    {this.state.bShowScanner ? (<VideoDecode></VideoDecode>) : ""}
                    {this.state.bShowImgDecode ? (<ImgDecode></ImgDecode>) : ""}
                </div>
            </div>
        );
    }
}
export default HelloWorld;

NOTE :

The method loadWasm() initializes the library in the background.

Define the style of the element in HelloWorld.css

.helloWorld {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    color: #455A64;
}

h1 {
    font-size: 1.5em;
}

button {
    font-size: 1.5rem;
    margin: 1.5vh 0;
    border: 1px solid black;
    background-color: white;
    color: black;
}

.container {
    margin: 2vmin auto;
    text-align: center;
    font-size: medium;
    width: 80vw;
}

Add the `HelloWorld` component to `App.tsx`

Edit the file App.tsx to be like this

import React from 'react';
import './App.css';
import HelloWorld from './components/HelloWorld/HelloWorld';

function App() {
  return (
    <div className="App">
      <HelloWorld></HelloWorld>
    </div>
  );
}

export default App;

Try running the project.

npm start

If you have followed all the steps correctly, you should now have a functioning page that allows you to scan barcodes from a webcam or a built-in camera. Additionally, if you want to decode a local image, you can click the Image Decode button and select the image you want to decode. Any barcodes that are detected will be displayed in a dialog.

Development server

Runs the app in the development mode.
Open “http://localhost:3000” to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

Build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

Support

If you have any questions, feel free to contact Dynamsoft support via email or live chat via the “Chat” button.