Summary
The default HTML data provider — webCustomData in src/languageFacts/data/webCustomData.ts, generated from @vscode/web-custom-data via build/generateData.js — contains 116 tags, all HTML. There are no entries for SVG elements (svg, path, circle, rect, g, …) or MathML elements (math, mrow, mi, …), even though SVG and MathML are routinely embedded in HTML documents.
As a result:
- Hovering a
<svg>, <path>, <math>, <mrow> etc. returns no info.
- Attribute completion for those elements returns nothing (no
viewBox, d, cx, xmlns, etc.).
- Typos in SVG/MathML attribute names are not flagged.
This affects every consumer that doesn't ship its own SVG/MathML custom data — i.e. effectively all of them: VS Code's built-in HTML server, volar-service-html, Vue's @vue/language-service, Glint (Ember), Astro, Svelte, etc. I checked Vue's language-tools and Glint, and neither adds SVG/MathML data — both just rely on the default provider.
Quick verification against a fresh install (uses the public API):
mkdir /tmp/repro && cd /tmp/repro
npm init -y >/dev/null
npm i vscode-html-languageservice
node --input-type=module -e "
import { getDefaultHTMLDataProvider } from 'vscode-html-languageservice';
const tags = getDefaultHTMLDataProvider().provideTags().map(t => t.name);
console.log('total tags:', tags.length);
for (const t of ['svg','path','circle','rect','g','math','mrow','mi','div','td']) {
console.log(t.padEnd(6), tags.includes(t));
}
"
# total tags: 116
# svg false
# path false
# circle false
# rect false
# g false
# math false
# mrow false
# mi false
# div true
# td trueRepro (plain .html in VS Code)
<!DOCTYPE html>
<html>
<body>
<td></td> <!-- hover: shows MDN description, attributes autocomplete -->
<svg><path d="M0 0"/></svg> <!-- hover on <svg> or <path>: nothing; no attribute completion -->
<math><mrow></mrow></math> <!-- hover on <math> or <mrow>: nothing -->
</body>
</html>Open this file in any editor backed by vscode-html-languageservice (VS Code's built-in HTML support is sufficient). Hover and tab-completion work for <td>/<div> but produce nothing for the SVG/MathML tags.
Code path that returns the empty result for SVG/MathML lookups:
src/services/htmlHover.ts:33-56 — getTagHover iterates providers, matches by name, returns null when nothing matches.src/services/htmlCompletion.ts:92, 157 — same per-provider iteration for tag/attribute completions.- The only built-in provider is
webCustomData, which has no SVG/MathML.
Proposal
Two non-exclusive options, in order of scope:
-
Ship SVG and MathML data in the default provider (or as separate built-in providers that are on by default). The data could be sourced/maintained alongside @vscode/web-custom-data — MDN's mdn-data and web-platform-dx/web-features already publish element/attribute metadata for both. This is the minimal fix and benefits every downstream consumer immediately.
-
Expose ready-made SVG and MathML IHTMLDataProviders as named exports that consumers can opt into via getCustomData. This is a smaller surface change and lets consumers continue gating on language id, but every consumer still has to wire it up themselves.
Summary
The default HTML data provider —
webCustomDatainsrc/languageFacts/data/webCustomData.ts, generated from@vscode/web-custom-dataviabuild/generateData.js— contains 116 tags, all HTML. There are no entries for SVG elements (svg,path,circle,rect,g, …) or MathML elements (math,mrow,mi, …), even though SVG and MathML are routinely embedded in HTML documents.As a result:
<svg>,<path>,<math>,<mrow>etc. returns no info.viewBox,d,cx,xmlns, etc.).This affects every consumer that doesn't ship its own SVG/MathML custom data — i.e. effectively all of them: VS Code's built-in HTML server,
volar-service-html, Vue's@vue/language-service, Glint (Ember), Astro, Svelte, etc. I checked Vue'slanguage-toolsand Glint, and neither adds SVG/MathML data — both just rely on the default provider.Quick verification against a fresh install (uses the public API):
Repro (plain
.htmlin VS Code)Open this file in any editor backed by
vscode-html-languageservice(VS Code's built-in HTML support is sufficient). Hover and tab-completion work for<td>/<div>but produce nothing for the SVG/MathML tags.Code path that returns the empty result for SVG/MathML lookups:
src/services/htmlHover.ts:33-56—getTagHoveriterates providers, matches by name, returnsnullwhen nothing matches.src/services/htmlCompletion.ts:92, 157— same per-provider iteration for tag/attribute completions.webCustomData, which has no SVG/MathML.Proposal
Two non-exclusive options, in order of scope:
Ship SVG and MathML data in the default provider (or as separate built-in providers that are on by default). The data could be sourced/maintained alongside
@vscode/web-custom-data— MDN'smdn-dataandweb-platform-dx/web-featuresalready publish element/attribute metadata for both. This is the minimal fix and benefits every downstream consumer immediately.Expose ready-made SVG and MathML
IHTMLDataProviders as named exports that consumers can opt into viagetCustomData. This is a smaller surface change and lets consumers continue gating on language id, but every consumer still has to wire it up themselves.