Announcing: Work has started on CodeMirror 6

No, still not stable, or even documented, at all. I recommend waiting.

One feature I like is being able to highlight text - however I hate how you have to use Ctrl commands or inserting @h@ to highlight rows. I would like to mark lines like you do in Visual studio where you click on the numbered row and it highlights on the fly

There’s now documentation, and an npm package. There’s still features missing and bugs, and things will no doubt continue to change in breaking ways, but going forward those will be documented in the change log.

@marijn, will CM6 support running highlighter/tokenizer in a web worker out of the box? These are expensive operations so instead of debouncing via setTimeout it’d be awesome to run them in parallel instead.

No — communicating with web workers is still awkward and/or wasteful (either need to put data in a flat array or copy everything), I didn’t find a practical way to do that.

communicating with web workers is still awkward and/or wasteful (either need to put data in a flat array or copy everything),

You mean ideologically, I guess, right? Because performance-wise copying+transferring should be totally negligible compared to the actual parsing/highlighting both duration-wise and CPU-wise. That’s when there’s a lot of text, of course, so it might make sense to auto-switch to the worker mode when last several highlighting jobs ran longer than some threshold.