Tesseract.js is a pure Javascript port of the popular Tesseract OCR engine. Basically Tesseract.js is a javascript library that gets words in almost any language out of images.
This library supports over 60 languages, automatic text orientation and script detection, a simple interface for reading paragraph, word, and character bounding boxes. Tesseract.js can run either in a browser and on a server with NodeJS.
Image should be be sufficiently high resolution. Often, the same image will get much better results if you upscale it before calling recognize.