Fix ESM import compatibility using globalThis

[Copilot]

ESM imports in browsers fail because the UMD wrapper is invoked with this, which is undefined in ESM module context, causing root to be undefined.

Changes

• dist/opencv.js: Changed UMD wrapper invocation from }(this, function () { to }(globalThis, function () { on line 22
• dist/opencv.js.patch: Updated patch file to document the globalThis change alongside the existing Module variable fix

Technical Details

The UMD wrapper was using this to pass the global object as the root parameter. In ESM context, this at the top level is undefined, causing the error "Cannot set properties of undefined (setting 'cv')".

Using globalThis fixes this by providing a universal reference to the global object that works across all JavaScript environments:

• Browsers: globalThis === window
• Node.js: globalThis === global
• Web Workers: globalThis === self

// Before
}(this, function () {

// After  
}(globalThis, function () {

This single-line change eliminates the need for post-install patching scripts users were applying as workarounds, while maintaining full backward compatibility with CommonJS, AMD, and Web Worker environments.

The dist/opencv.js.patch file has been updated to document this change for future reference when building opencv.js from source.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>ES Module (ESM) import compatibility</issue_title>
<issue_description>I need this patch script in my package.json to have opencv-js work with import in the browser (testing on Edge).

  "scripts": {
    ...
    "fix-opencv-import": "replace \"if[(]typeof window==='object'[)][{]root.cv=factory[(][)];[}]\" \"if(typeof window==='object'){window.cv=factory();}\" node_modules/@techstark/opencv-js/dist/opencv.js",
    ...
  },

Thank you</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ES Module (ESM) import compatibility #44

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[ttt43ttt]

@copilot see #44 (comment)
I think we can use that way to fix it. No need to add new test.

[Copilot]

@copilot see #44 (comment)
I think we can use that way to fix it. No need to add new test.

Done! Changed to use globalThis instead of this on line 22 as suggested in the issue comment. This is a cleaner solution that fixes the root cause. Removed the test file as requested. All existing tests pass. (commit f2b867f)