/ Miscellaneous

React component for reading QR codes from webcam

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

GitHub