Pros of zxing

• Multi-format support: Handles various barcode formats beyond QR codes
• Mature and widely adopted: Extensive community support and battle-tested in production
• Available in multiple programming languages: Java, C++, and more

Cons of zxing

• Larger codebase and dependencies: May be overkill for simple QR code scanning
• Steeper learning curve: More complex API compared to jsQR
• Potentially slower performance for web-based applications

Code Comparison

jsQR:

const code = jsQR(imageData.data, imageData.width, imageData.height);
if (code) {
  console.log("Found QR code", code.data);
}

zxing:

LuminanceSource source = new BufferedImageLuminanceSource(image);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
Result result = new MultiFormatReader().decode(bitmap);
System.out.println("Found QR code: " + result.getText());

The code examples demonstrate that jsQR offers a simpler API for QR code detection in JavaScript, while zxing requires more setup but provides greater flexibility for various barcode formats in Java.

Pros of html5-qrcode

• Offers a higher-level API for easier integration into web applications
• Provides built-in support for camera access and real-time scanning
• Includes a user interface component for QR code scanning

Cons of html5-qrcode

• Larger file size and potentially higher resource usage
• May have slower performance for processing individual images
• Less flexibility for custom implementations

Code Comparison

html5-qrcode:

Html5Qrcode.getCameras().then(devices => {
    if (devices && devices.length) {
        var cameraId = devices[0].id;
        const html5QrCode = new Html5Qrcode("reader");
        html5QrCode.start(
            cameraId,
            {
                fps: 10,
                qrbox: 250
            },
            qrCodeMessage => {
                console.log(`QR Code detected: ${qrCodeMessage}`);
            },
            errorMessage => {
                // parse error, ignore it.
            })
        .catch(err => {
            // Start failed, handle it.
        });
    }
});

jsQR:

const canvas = document.getElementById('canvas');
const context = canvas.getContext('2d');
const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
const code = jsQR(imageData.data, imageData.width, imageData.height);
if (code) {
    console.log("Found QR code", code.data);
}

Pros of qr-scanner

• Higher performance due to WebAssembly implementation
• Supports scanning from video streams, enabling real-time QR code detection
• More actively maintained with recent updates and bug fixes

Cons of qr-scanner

• Larger file size due to WebAssembly module
• May have compatibility issues with older browsers that don't support WebAssembly

Code Comparison

qr-scanner:

import QrScanner from 'qr-scanner';

const qrScanner = new QrScanner(
    videoElem,
    result => console.log('decoded qr code:', result),
    { /* options */ },
);
qrScanner.start();

jsQR:

import jsQR from 'jsqr';

const code = jsQR(imageData.data, imageData.width, imageData.height);
if (code) {
    console.log("Found QR code", code.data);
}

Both libraries offer straightforward APIs for QR code scanning, but qr-scanner provides a more streamlined approach for video-based scanning, while jsQR requires manual frame extraction and processing for real-time scanning from video sources.

Pros of Instascan

• Real-time scanning capability for live video streams
• Supports multiple cameras and easy camera switching
• Includes a simple UI component for quick integration

Cons of Instascan

• Less actively maintained (last update in 2017)
• Limited to QR codes only, doesn't support other barcode formats
• Requires access to camera, which may not be suitable for all use cases

Code Comparison

Instascan:

let scanner = new Instascan.Scanner({ video: document.getElementById('preview') });
scanner.addListener('scan', function (content) {
  console.log(content);
});
Instascan.Camera.getCameras().then(function (cameras) {
  if (cameras.length > 0) {
    scanner.start(cameras[0]);
  }
}).catch(function (e) {
  console.error(e);
});

jsQR:

const code = jsQR(imageData.data, imageData.width, imageData.height);
if (code) {
  console.log("Found QR code", code.data);
}

jsQR offers a more lightweight approach, working directly with image data without requiring camera access. It's more flexible for various input sources but requires more setup for real-time scanning. Instascan provides an out-of-the-box solution for live video scanning but is limited to QR codes and requires camera access.