Comment by slopinthebag

I mentioned this elsewhere, but it's not actually doing any of what you describe. It's rendering the text to a canvas and then measuring that. I don't see any benchmarks that indicate it's faster than just sticking it in a <p> tag, and not any clear indication that it would be. It's certainly not implementing the full algorithm for text rendering in a browser.

It certainly seems to provide an API for analysing text layouts, but all of the computation still goes through the browser's native layout system.