regexp-tree
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DmitrySoshnikov
Can it be used to give Firefox/Safari full ES2018 Regex support?
(My "issue" is documentation correction, and request for documentation clarification.)
The README, under lookbehind assertions is out of date:
NOTE: Lookbehind assertions are not yet supported by JavaScript RegExp. It is an ECMAScript proposal which is at stage 3 at the moment.
It should say they were added in ES2018.
If you wanted to include more detail:
It is supported since Chrome 62, Opera 49, Edge 79, Node since 8 with --harmony flag (or Node 10 without any flags). Firefox (https://bugzilla.mozilla.org/show_bug.cgi?id=1225665) say it is being worked on, as of Oct 2019, but no signs of that as of Jan 2020. Safari/Webkit (https://bugs.webkit.org/show_bug.cgi?id=174931) have been ignoring it since July 2017.
My main question: it wasn't clear to me if I could use regexp-tree as a drop-in replacement for ES2018 RegExp (specifically named capture groups and lookbehind assertions) on Firefox and Safari. If it is possible, does anyone have an example, or a link to a blog or tutorial (or github project) showing this? And if impossible, is it possible to make that clearer in the README?
From #5 and #66 I think the answer is that it is impossible; however #27 (and the commits it links to) seem to be saying the opposite?
(My motivation is I don't like having to tell people they have to use Chrome; but in the case of wanting to show a demo on an iPad, even that is not an option.)
@DarrenCook, thanks for reporting the issue with the README.
It should say they were added in ES2018.
Yes, we should add it. I'll appreciate a PR for this, or will update it once reach it.
As to your main question: some things can be compat-transpiled, e.g. named capturing groups. Babel added support for it using regexp-tree at some point. There is also https://github.com/DmitrySoshnikov/babel-plugin-transform-modern-regexp which also has partial support for it (transpiles, and runtime support needs to be added).
Lookbehind assertions is harder to transpiler, but we can continue investigating it.
