How to load and initialize OpenCV.js in the browser?

There are several ways to load OpenCV.js in the browser:

1. Direct CDN Import (Recommended)

html
<script async src="https://docs.opencv.org/4.8.0/opencv.js" onload="onOpenCvReady()" type="text/javascript"></script>

2. Local Download Import

Download the opencv.js file from the OpenCV official website and place it in your project:

html
<script src="path/to/opencv.js"></script>

3. Using npm Package

bash
npm install @techstark/opencv-js

javascript
import cv from '@techstark/opencv-js';

Loading Considerations

1. Asynchronous Loading: The opencv.js file is large (about 8-10MB), so it's recommended to use the async attribute for asynchronous loading
2. Loading Detection: Use cv['onRuntimeInitialized'] to confirm loading is complete

javascript
function onOpenCvReady() {
  console.log('OpenCV.js is ready');
  // Start using OpenCV features
}

1. Performance Optimization:

   • Use compressed version (opencv.js.gz) to reduce loading time
   • Configure CDN caching strategies
   • Consider using Service Worker for caching

2. Compatibility:

   • Requires browser support for WebAssembly
   • IE browser not supported (needs polyfill or fallback solution)

Best Practices

javascript
// Check if OpenCV is loaded successfully
if (typeof cv !== 'undefined' && cv.getBuildInformation) {
  console.log('OpenCV.js loaded successfully');
  console.log(cv.getBuildInformation());
}