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JavaScript Hello World Sample - Next.js
Next.js is an open-source development framework built on top of Node.js enabling React based web applications functionalities such as server-side rendering and generating static websites. Follow this guide to learn how to implement Dynamsoft Barcode Reader JavaScript SDK (hereafter called “the library”) into a Next.js application. Note that in this sample we will use TypeScript
.
Official Sample
Preparation
Make sure you have node installed. node 14.21.3
and next 13.2.4
are used in the example below.
Create the sample project
Create a Bootstrapped Raw Next.js Application
npx create-next-app@latest --typescript
CD to the root directory of the application and install the dependencies
npm install dynamsoft-javascript-barcode
Start to implement
Add a file dbr.ts at the root of the application to configure the library
import { BarcodeReader } from 'dynamsoft-javascript-barcode';
BarcodeReader.license = 'DLS2eyJvcmdhbml6YXRpb25JRCI6IjIwMDAwMSJ9';
BarcodeReader.engineResourcePath = "https://cdn.jsdelivr.net/npm/dynamsoft-javascript-barcode/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.
Create a directory “components” and create the following files inside it to represent three components
- VideoDecode.tsx
- ImgDecode.tsx
- HelloWorld.tsx
Edit the VideoDecode
component
- In VideoDecode.tsx, add code for initializing and destroying the
BarcodeScanner
instance. TheVideoDecode
component usesBarcodeScanner
class of the library to help decode barcodes via camera.
import { BarcodeScanner } from "dynamsoft-javascript-barcode";
import React from 'react';
import styles from '@/styles/VideoDecode.module.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={styles["component-barcode-scanner"]}>
<svg className={styles["dce-bg-loading"]+" "+"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={styles["dce-bg-camera"]+" "+"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={styles["dce-video-container"]+" "+"dce-video-container"}></div>
<div className={styles["dce-scanarea"]+" "+"dce-scanarea"}>
<div className={styles["dce-scanlight"]+" "+"dce-scanlight"}></div>
</div>
<div className={styles["div-select-container"]+" "+"div-select-container"}>
<select className={styles["dce-sel-camera"]+" "+"dce-sel-camera"}></select>
<select className={styles["dce-sel-resolution"]+" "+"dce-sel-resolution"}></select>
</div>
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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!);
- To release resources timely, the
BarcodeScanner
instance is destroyed with the component in the callbackcomponentWillUnmount
.- The component should never update (check the code for
shouldComponentUpdate()
) so that events bound to the UI stay valid.
- Create ‘VideoDecode.module.css’ under ‘/styles/’ and define the style of the component in it
.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%;}}
Edit the ImgDecode
component
- In ImgDecode.tsx, add code for initializing and destroying the
BarcodeReader
instance. TheImgDecode
component usesBarcodeReader
class of the library to help decode barcodes in an image.
import React, { ChangeEvent, Component } from 'react'
import { BarcodeReader } from "dynamsoft-javascript-barcode";
import styles from '@/styles/ImgDecode.module.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={styles.ImgDecode}><input type="file" onChange={this.decodeImg} /></div>
)
}
}
- Create ‘ImgDecode.module.css’ under ‘/styles/’ and define the style of the component in it
.ImgDecode {
display: flex;
justify-content: center;
align-items: center;
border: 1px solid black
}
Edit the HelloWorld component
- Add
VideoDecode
andImgDecode
components in HelloWorld.tsx
import React from 'react';
import VideoDecode from './VideoDecode';
import ImgDecode from './ImgDecode';
import "../dbr"; // import side effects. The license, engineResourcePath, so on.
import { BarcodeReader } from "dynamsoft-javascript-barcode";
import styles from '@/styles/HelloWorld.module.css'
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={styles.helloWorld}>
<h1 className={styles.header}>Hello World for Next.js</h1>
<div>
<button className={styles.button} style= onClick={this.showScanner}>Video Decode</button>
<button className={styles.button} style= onClick={this.showImgDecode}>Image Decode</button>
</div>
<div className={styles.container}>
{this.state.bShowScanner ? (<VideoDecode></VideoDecode>) : ""}
{this.state.bShowImgDecode ? (<ImgDecode></ImgDecode>) : ""}
</div>
</div>
);
}
}
export default HelloWorld;
- Create ‘HelloWorld.module.css’ under ‘/styles/’ and define the style of the component in it
.helloWorld {
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
width: 100%;
height: 100%;
color: #455A64;
}
.header {
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;
width: 100%;
}
Add the HelloWorld component to /pages/index.tsx
In index.tsx, import the HelloWorld
component:
import HelloWorld from '../components/HelloWorld'
Change the <main> tag like this:
<main className={styles.main}>
<div className={styles.UIElement}>
<HelloWorld />
</div>
</main>
- Define the style of the “App” element in styles/Home.module.css
.UIElement {
margin: 2vmin auto;
text-align: center;
font-size: medium;
width: 80vw;
}
- Try running the project.
npm run dev
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.
Project Setup
npm install
Compile and Hot-Reload for Development
npm run dev
Type-Check, Compile and Minify for Production
npm run build