Build a React.js QRCode Scanner Using Webcam & Image in Browser Using jsqr Library in JSX

npm i jsqr

And after that create a App.jsx file and copy paste the following code

App.jsx

import React, { useState, useRef, useEffect } from 'react';
import jsQR from 'jsqr';

const QRCodeScanner = () => {
  const [scanResult, setScanResult] = useState('');
  const [errorMessage, setErrorMessage] = useState('');
  const [isCopied, setIsCopied] = useState(false);
  const [scanMode, setScanMode] = useState('upload'); // 'upload' or 'webcam'
  const [isScanning, setIsScanning] = useState(false);
  
  const fileInputRef = useRef(null);
  const videoRef = useRef(null);
  const canvasRef = useRef(null);
  const streamRef = useRef(null);

  // Clean up webcam stream when component unmounts
  useEffect(() => {
    return () => {
      if (streamRef.current) {
        const tracks = streamRef.current.getTracks();
        tracks.forEach(track => track.stop());
      }
    };
  }, []);

  // Handle file upload
  const handleFileUpload = (e) => {
    const file = e.target.files[0];
    setErrorMessage('');
    
    if (!file) return;
    
    if (!file.type.match('image.*')) {
      setErrorMessage('Please select an image file');
      return;
    }

    const reader = new FileReader();
    reader.onload = (event) => {
      const img = new Image();
      img.onload = () => processImage(img);
      img.src = event.target.result;
    };
    reader.readAsDataURL(file);
  };

  // Process image to find QR code
  const processImage = (img) => {
    const canvas = canvasRef.current;
    canvas.width = img.width;
    canvas.height = img.height;
    
    const ctx = canvas.getContext('2d');
    ctx.drawImage(img, 0, 0);
    
    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const code = jsQR(imageData.data, imageData.width, imageData.height);
    
    if (code) {
      setScanResult(code.data);
      setErrorMessage('');
    } else {
      setErrorMessage('No QR code found in the image');
      setScanResult('');
    }
  };

  // Start webcam scanning
  const startWebcamScan = async () => {
    try {
      setErrorMessage('');
      setIsScanning(true);
      
      const stream = await navigator.mediaDevices.getUserMedia({ 
        video: { facingMode: "environment" } 
      });
      
      streamRef.current = stream;
      videoRef.current.srcObject = stream;
      videoRef.current.play();
      
      requestAnimationFrame(scanVideoFrame);
    } catch (error) {
      setIsScanning(false);
      setErrorMessage(`Cannot access camera: ${error.message}`);
    }
  };

  // Stop webcam scanning
  const stopWebcamScan = () => {
    if (streamRef.current) {
      const tracks = streamRef.current.getTracks();
      tracks.forEach(track => track.stop());
      streamRef.current = null;
    }
    setIsScanning(false);
  };

  // Process video frames to find QR code
  const scanVideoFrame = () => {
    if (!isScanning) return;
    
    const video = videoRef.current;
    const canvas = canvasRef.current;
    
    if (video.readyState === video.HAVE_ENOUGH_DATA) {
      canvas.width = video.videoWidth;
      canvas.height = video.videoHeight;
      
      const ctx = canvas.getContext('2d');
      ctx.drawImage(video, 0, 0);
      
      const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
      const code = jsQR(imageData.data, imageData.width, imageData.height);

      if (code) {
        setScanResult(code.data);
        stopWebcamScan();
        return;
      }
    }
    
    requestAnimationFrame(scanVideoFrame);
  };

  // Switch between scanning modes
  const switchScanMode = (mode) => {
    if (mode === scanMode) return;
    
    // Clean up current mode
    if (scanMode === 'webcam' && isScanning) {
      stopWebcamScan();
    }
    
    setScanMode(mode);
    setScanResult('');
    setErrorMessage('');
    
    if (mode === 'webcam') {
      startWebcamScan();
    }
  };

  // Copy result to clipboard
  const copyToClipboard = () => {
    if (!scanResult) return;
    
    navigator.clipboard.writeText(scanResult)
      .then(() => {
        setIsCopied(true);
        setTimeout(() => setIsCopied(false), 2000);
      })
      .catch(err => {
        setErrorMessage(`Failed to copy: ${err.message}`);
      });
  };

  return (
    <div className="max-w-md mx-auto p-6 bg-white rounded-lg shadow-lg">
      <h1 className="text-2xl font-bold text-center mb-6">QR Code Scanner</h1>
      
      {/* Scan Mode Tabs */}
      <div className="flex mb-6 border-b">
        <button
          onClick={() => switchScanMode('upload')}
          className={`py-2 px-4 ${scanMode === 'upload' 
            ? 'border-b-2 border-blue-500 text-blue-500 font-medium' 
            : 'text-gray-500'}`}
        >
          Upload Image
        </button>
        <button
          onClick={() => switchScanMode('webcam')}
          className={`py-2 px-4 ${scanMode === 'webcam' 
            ? 'border-b-2 border-blue-500 text-blue-500 font-medium' 
            : 'text-gray-500'}`}
        >
          Use Webcam
        </button>
      </div>
      
      {/* File Upload Interface */}
      {scanMode === 'upload' && (
        <div className="mb-6">
          <div className="flex items-center justify-center">
            <label className="flex flex-col items-center px-4 py-6 bg-white text-blue-500 rounded-lg shadow-lg tracking-wide uppercase border border-blue-500 cursor-pointer hover:bg-blue-500 hover:text-white">
              <svg className="w-8 h-8" fill="currentColor" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20">
                <path d="M16.88 9.1A4 4 0 0 1 16 17H5a5 5 0 0 1-1-9.9V7a3 3 0 0 1 4.52-2.59A4.98 4.98 0 0 1 17 8c0 .38-.04.74-.12 1.1zM11 11h3l-4-4-4 4h3v3h2v-3z" />
              </svg>
              <span className="mt-2 text-base leading-normal">Select QR Image</span>
              <input 
                type="file" 
                accept="image/*" 
                className="hidden" 
                onChange={handleFileUpload}
                ref={fileInputRef}
              />
            </label>
          </div>
        </div>
      )}
      
      {/* Webcam Interface */}
      {scanMode === 'webcam' && (
        <div className="mb-6">
          <div className="relative">
            <video
              ref={videoRef}
              className="w-full h-64 bg-black object-cover"
              muted
              playsInline
            />
            <div className="absolute inset-0 border-2 border-blue-500 border-dashed pointer-events-none"></div>
          </div>
          <div className="mt-4 text-center">
            {isScanning ? (
              <p className="text-sm text-gray-600">Scanning for QR Code...</p>
            ) : (
              <button
                onClick={startWebcamScan}
                className="bg-blue-500 text-white px-4 py-2 rounded hover:bg-blue-600"
                style={{backgroundColor: '#3b82f6'}}
              >
                Start Scanning
              </button>
            )}
          </div>
        </div>
      )}
      
      {/* Hidden Canvas for Processing */}
      <canvas ref={canvasRef} className="hidden"></canvas>
      
      {/* Error Messages */}
      {errorMessage && (
        <div className="mb-4 p-2 bg-red-100 text-red-700 rounded">
          {errorMessage}
        </div>
      )}
      
      {/* Results Display */}
      {scanResult && (
        <div className="mt-6">
          <h2 className="text-lg font-semibold mb-2">Scan Result:</h2>
          <div className="flex">
            <div className="flex-grow p-3 bg-gray-100 rounded-l border border-r-0 border-gray-300 break-all overflow-auto max-h-32">
              {scanResult}
            </div>
            <button
              onClick={copyToClipboard}
              className="bg-gray-200 hover:bg-gray-300 px-3 rounded-r border border-gray-300 flex items-center justify-center"
              title="Copy to clipboard"
            >
              <svg xmlns="http://www.w3.org/2000/svg" className="h-5 w-5" viewBox="0 0 20 20" fill="currentColor">
                <path d="M8 3a1 1 0 011-1h2a1 1 0 110 2H9a1 1 0 01-1-1z" />
                <path d="M6 3a2 2 0 00-2 2v11a2 2 0 002 2h8a2 2 0 002-2V5a2 2 0 00-2-2 3 3 0 01-3 3H9a3 3 0 01-3-3z" />
              </svg>
            </button>
          </div>
          {isCopied && (
            <p className="text-sm text-green-600 mt-1">Copied to clipboard!</p>
          )}
        </div>
      )}
      
      {/* Scan Again Button (when result is shown) */}
      {scanResult && (
        <div className="mt-4 text-center">
          <button 
            onClick={() => {
              setScanResult('');
              setErrorMessage('');
              if (scanMode === 'upload') {
                if (fileInputRef.current) fileInputRef.current.value = '';
              } else if (scanMode === 'webcam') {
                startWebcamScan();
              }
            }}
            className="bg-blue-500 text-white px-4 py-2 rounded hover:bg-blue-600"
            style={{backgroundColor: '#3b82f6'}}
          >
            Scan Another Code
          </button>
        </div>
      )}
    </div>
  );
};

export default QRCodeScanner;

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import React, { useState, useRef, useEffect } from 'react';

import jsQR from 'jsqr';

const QRCodeScanner = () => {

const [scanResult, setScanResult] = useState('');

const [errorMessage, setErrorMessage] = useState('');

const [isCopied, setIsCopied] = useState(false);

const [scanMode, setScanMode] = useState('upload'); // 'upload' or 'webcam'

const [isScanning, setIsScanning] = useState(false);

const fileInputRef = useRef(null);

const videoRef = useRef(null);

const canvasRef = useRef(null);

const streamRef = useRef(null);

// Clean up webcam stream when component unmounts

useEffect(() => {

return () => {

if (streamRef.current) {

const tracks = streamRef.current.getTracks();

tracks.forEach(track => track.stop());

}

};

}, []);

// Handle file upload

const handleFileUpload = (e) => {

const file = e.target.files[0];

setErrorMessage('');

if (!file) return;

if (!file.type.match('image.*')) {

setErrorMessage('Please select an image file');

return;

}

const reader = new FileReader();

reader.onload = (event) => {

const img = new Image();

img.onload = () => processImage(img);

img.src = event.target.result;

};

reader.readAsDataURL(file);

};

// Process image to find QR code

const processImage = (img) => {

const canvas = canvasRef.current;

canvas.width = img.width;

canvas.height = img.height;

const ctx = canvas.getContext('2d');

ctx.drawImage(img, 0, 0);

const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);

const code = jsQR(imageData.data, imageData.width, imageData.height);

if (code) {

setScanResult(code.data);

setErrorMessage('');

} else {

setErrorMessage('No QR code found in the image');

setScanResult('');

}

};

// Start webcam scanning

const startWebcamScan = async () => {

try {

setErrorMessage('');

setIsScanning(true);

const stream = await navigator.mediaDevices.getUserMedia({

video: { facingMode: "environment" }

});

streamRef.current = stream;

videoRef.current.srcObject = stream;

videoRef.current.play();

requestAnimationFrame(scanVideoFrame);

} catch (error) {

setIsScanning(false);

setErrorMessage(`Cannot access camera: ${error.message}`);

}

};

// Stop webcam scanning

const stopWebcamScan = () => {

if (streamRef.current) {

const tracks = streamRef.current.getTracks();

tracks.forEach(track => track.stop());

streamRef.current = null;

}

setIsScanning(false);

};

// Process video frames to find QR code

const scanVideoFrame = () => {

if (!isScanning) return;

const video = videoRef.current;

const canvas = canvasRef.current;

if (video.readyState === video.HAVE_ENOUGH_DATA) {

canvas.width = video.videoWidth;

canvas.height = video.videoHeight;

const ctx = canvas.getContext('2d');

ctx.drawImage(video, 0, 0);

const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);

const code = jsQR(imageData.data, imageData.width, imageData.height);

if (code) {

setScanResult(code.data);

stopWebcamScan();

return;

}

requestAnimationFrame(scanVideoFrame);

};

// Switch between scanning modes

const switchScanMode = (mode) => {

if (mode === scanMode) return;

// Clean up current mode

if (scanMode === 'webcam' && isScanning) {

stopWebcamScan();

}

setScanMode(mode);

setScanResult('');

setErrorMessage('');

if (mode === 'webcam') {

startWebcamScan();

}

};

// Copy result to clipboard

const copyToClipboard = () => {

if (!scanResult) return;

navigator.clipboard.writeText(scanResult)

.then(() => {

setIsCopied(true);

setTimeout(() => setIsCopied(false), 2000);

})

.catch(err => {

setErrorMessage(`Failed to copy: ${err.message}`);

});

};

return (

<h1 className="text-2xl font-bold text-center mb-6">QR Code Scanner</h1>

{/* Scan Mode Tabs */}

<button

onClick={() => switchScanMode('upload')}

className={`py-2 px-4 ${scanMode === 'upload'

? 'border-b-2 border-blue-500 text-blue-500 font-medium'

: 'text-gray-500'}`}

Upload Image

</button>

<button

onClick={() => switchScanMode('webcam')}

className={`py-2 px-4 ${scanMode === 'webcam'

? 'border-b-2 border-blue-500 text-blue-500 font-medium'

: 'text-gray-500'}`}

Use Webcam

</button>

</div>

{/* File Upload Interface */}

{scanMode === 'upload' && (

</svg>

<span className="mt-2 text-base leading-normal">Select QR Image</span>

<input

type="file"

accept="image/*"

className="hidden"

onChange={handleFileUpload}

ref={fileInputRef}

</label>

</div>

)}

{/* Webcam Interface */}

{scanMode === 'webcam' && (

<video

ref={videoRef}

className="w-full h-64 bg-black object-cover"

muted

playsInline

</div>

{isScanning ? (

<p className="text-sm text-gray-600">Scanning for QR Code...</p>

) : (

<button

onClick={startWebcamScan}

className="bg-blue-500 text-white px-4 py-2 rounded hover:bg-blue-600"

style={{backgroundColor: '#3b82f6'}}

Start Scanning

</button>

)}

</div>

)}

{/* Hidden Canvas for Processing */}

{/* Error Messages */}

{errorMessage && (

{errorMessage}

</div>

)}

{/* Results Display */}

{scanResult && (

<h2 className="text-lg font-semibold mb-2">Scan Result:</h2>

{scanResult}

</div>

<button

onClick={copyToClipboard}

className="bg-gray-200 hover:bg-gray-300 px-3 rounded-r border border-gray-300 flex items-center justify-center"

title="Copy to clipboard"

</svg>

</button>

</div>

{isCopied && (

<p className="text-sm text-green-600 mt-1">Copied to clipboard!</p>

)}

</div>

)}

{/* Scan Again Button (when result is shown) */}

{scanResult && (

<button

onClick={() => {

setScanResult('');

setErrorMessage('');

if (scanMode === 'upload') {

if (fileInputRef.current) fileInputRef.current.value = '';

} else if (scanMode === 'webcam') {

startWebcamScan();

}

}}

className="bg-blue-500 text-white px-4 py-2 rounded hover:bg-blue-600"

style={{backgroundColor: '#3b82f6'}}

Scan Another Code

</button>

</div>

)}

</div>

);

};

export default QRCodeScanner;

Build a React.js QRCode Scanner Using Webcam & Image in Browser Using jsqr Library in JSX

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