Use KaTeX AST instead of reparsing the whole tree

[sandhose]

Right now remark-math uses KaTeX's renderToString method to generate HTML, then reparses it directly afterwards using rehype-parse.

This is expensive, but was necessary because KaTeX used to not expose their internal AST.

I opened a while ago an issue on their side to expose this AST in order to have better renderers. It seems like now they do. KaTeX/KaTeX#800 (comment)

It would be great if remark-math did the conversion from KaTeX's AST to HAST nodes directly, instead of parsing the stringified DOM tree

[Rokt33r]

Sounds reasonable!

[ibrahima]

Just to be clear, this is only applicable to remark-html-katex, right? remark-html itself has nothing to do with KaTeX, it's just parsing out LaTeX nodes for remark?

[wooorm]

@ibrahima This relates to rehype-katex and remark-html-katex. They both include an HTML parser because KaTeX spits out an HTML string that needs to be transformed into our AST.

I’ve reached out to KaTeX people again and may be able to work on using hast in KaTeX.

[wooorm]

I don’t think it’s useful to track this there as it’s tracked upstream. Closing.