Highlight JSX in plain old js2-mode

[jacksonrayhamilton]

JSX highlighting is currently available only if

• the user installs Emacs 27 and uses js-mode with js2-minor-mode enabled, or
• the user installs rjsx-mode.

It would be nice if JSX was also highlighted when plain ol’ js2-mode is enabled.

As we decided in #523, the highlighting that js-mode does won’t be inherited by js2-mode, because js2-mode highlights code based on its AST, not with font-lock-keywords.

Therefore, should we ever parse JSX nodes and add them to the AST (as proposed in #527), then during that parsing, we should also record the locations where faces should be applied to JSX so that it’s highlighted as such. It should be highlighted like SGML, just like js-mode does it in Emacs 27. This issue proposes such an improvement to js2-mode.

[dgutov]

Sure. Except the current js2-mode parser doesn't read the nodes in good enough detail to do that. rjsx-mode already does that, I think simply during parsing.

So I think this issue is a subset of 527.

[glepnir]

It does seem to have good support in emacs28, but the highlighting seems to be missing.

[dgutov]

Highlighting of..?

[glepnir]

syntax highlight .open js2-mode .

[dgutov]

Hmm, yes. That's correct. js-mode is a lot more subtle in syntax highlighting.

But that's a historical thing. You can file a feature request for it to highlight more things.

[glepnir]

I use the color-indentifilers-mode with js-mode on emacs28 got a good syntax highlight

[jacksonrayhamilton]

@taigacute, this issue is about highlighting JSX syntax (and only that syntax) in js2-mode, in the absence of other software. It’s not seeking the shortest path to a personal solution, or any alternatives or workarounds for any other scenarios.

We’re glad you found something that works for you, but this is not the place to the post it, unless it is relevant to the implementation proposed in the issue description.

[dgutov]

Indeed. Sorry, I also played a part in side-tracking this discussion.