Upgrading from v2 to v5 Guide about tesseract.js

[Balearica]

[Archive] v2 to v4 Guide

The following comment contains the old guide for upgrading from v2 to v4. Users are encouraged to update to the latest version (v5), but this is still provided for informational purposes.

Changes Impacting Most Users

1. createWorker is now async
   • In most code this means worker = Tesseract.createWorker() should be replaced with worker = await Tesseract.createWorker()
2. worker.load is no longer needed (createWorker now returns worker pre-loaded)
   • Simply delete worker.load from existing code

Changes Impacting Fewer Users

1. Electron users
   • Use the browser version of Tesseract.js
     • In v2, many users used the Node.js version
2. Users of getPDF function
   • This function has been replaced by pdf recognize option (#488)
   • See browser and node examples for usage
3. Users who set cacheMethod: 'none' or cacheMethod: 'refresh' as workaround for caching bug
   • This workaround can be removed, the underlying bug has been fixed (see this comment)
4. Users who set the optional corePath argument
   • You will need to point corePath to a compatible version of Tesseract.js-core (the latest version of Tesseract.js should be used with the latest version of Tesseract.js-core)
   • For significantly faster performance, set corePath to a directory that includes both tesseract-core.wasm.js and tesseract-core-simd.wasm.js
     • See this comment for explanation
5. Node.js <14 users
   • Node.js v14 is now the earliest version supported