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fix(emcn): keep Prism grammar registrations in bundle, never throw on missing grammar #5293

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Merged
waleedlatif1 merged 1 commit into from
Jun 30, 2026
Merged

fix(emcn): keep Prism grammar registrations in bundle, never throw on missing grammar #5293

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28 changes: 25 additions & 3 deletions packages/emcn/src/components/code/prism.ts
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
import { highlight, languages } from 'prismjs'
import { type Grammar, languages, highlight as prismHighlight } from 'prismjs'
import 'prismjs/components/prism-javascript'
import 'prismjs/components/prism-python'
import 'prismjs/components/prism-json'
Expand All @@ -10,10 +10,32 @@ import 'prismjs/components/prism-json'
* shared `Prism.languages` registry), which marks any module that statically
* imports them as having side effects and therefore non-tree-shakeable. Keeping
* them here — rather than in `code.tsx` — ensures Prism only enters bundles that
* actually import `highlight`/`languages`, instead of every consumer of the
* shared `@sim/emcn` barrel (which re-exports `Code`).
* actually import these utilities, instead of every consumer of the shared
* `@sim/emcn` barrel (which re-exports `Code`).
*
* `code.tsx` itself never imports this module statically; it loads it lazily via
* dynamic `import()` on first highlight.
*
* `highlight` is a local wrapper rather than a re-export of Prism's `highlight`.
* A bare re-export lets bundlers resolve the binding straight from `prismjs` and
* skip this module's body, dropping the grammar registrations above so
* `languages.json` (etc.) become `undefined` at runtime. Owning the function
* keeps the registrations in the dependency graph and lets us degrade to escaped
* plaintext when a grammar is missing instead of throwing.
*/

function escapeHtml(text: string): string {
return text.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;')
}

/**
* Highlights `code` with the given Prism `grammar`, returning HTML markup.
* Falls back to escaped plaintext when `grammar` is undefined so a missing or
* unregistered language never throws `The language "<x>" has no grammar.`.
*/
function highlight(code: string, grammar: Grammar | undefined, language: string): string {
if (!grammar) return escapeHtml(code)
return prismHighlight(code, grammar, language)
}

export { highlight, languages }
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