React component for reading QR codes from webcam
react-qr-reader
A React component for reading QR codes from the webcam. It uses the WebRTC standards for reading webcam data and jsQR is used for detecting QR codes in that data. To optimise the speed and experience, a web-worker is used to offload the heavy QR code algorithm on a separate process. The web worker is inlined and loaded on creation of the component.
Known Issues
- Due to browser implementations the camera can only be accessed over https or localhost.
- In Firefox a prompt will be shown to the user asking which camera to use, so
facingMode
will not affect it. - On IOS 11 it is only supported on Safari and not on Chrome or Firefox due to Apple making the API not available to 3th party browsers.
Install
npm install --save react-qr-reader
Example
import React, { Component } from "react";
import QrReader from "react-qr-reader";
class Test extends Component {
constructor(props) {
super(props);
this.state = {
delay: 300,
result: "No result"
};
this.handleScan = this.handleScan.bind(this);
}
handleScan(data) {
if (data) {
this.setState({
result: data
});
}
}
handleError(err) {
console.error(err);
}
render() {
return (
<div>
<QrReader
delay={this.state.delay}
onError={this.handleError}
onScan={this.handleScan}
style={{ width: "100%" }}
/>
<p>{this.state.result}</p>
</div>
);
}
}
Props
Events
Prop | Argument | Description |
---|---|---|
onScan | result |
Scan event handler. Called every scan with the decoded value or null if no QR code was found. |
onError | Error |
Called when an error occurs. |
onLoad | none | Called when the component is ready for use. |
onImageLoad | img onLoad event | Called when the image in legacyMode is loaded. |
Options
Prop | Type | Default | Description |
---|---|---|---|
delay | number or false |
500 |
The delay between scans in milliseconds. To disable the interval pass in false . |
facingMode | user or environment |
environment |
Specify which camera should be used (if available). |
resolution | number | 600 |
The resolution of the video (or image in legacyMode). Larger resolution will increase the accuracy but it will also slow down the processing time. |
style | a valid React style | none | Styling for the container element. Warning The preview will always keep its 1:1 aspect ratio. |
className | string | none | ClassName for the container element. |
showViewFinder | boolean | true |
Show or hide the build in view finder. See demo |
constraints | object | null |
Use custom camera constraints that the override default behavior. MediaTrackConstraints |
legacyMode | boolean | false |
If the device does not allow camera access (e.g. IOS Browsers, Safari) you can enable legacyMode to allow the user to take a picture (On a mobile device) or use an existing one. To trigger the image dialog just call the method openImageDialog from the parent component. Warning You must call the method from a user action (eg. click event on some element). |
Dev
Install dependencies
npm install
Build
npm run build
Demo
npm run storybook
Linting
npm run lint
Tested platforms
- Chrome macOs & Android
- Firefox macOs & Android
- Safari macOs & IOS