Fix CJS build to actually emit CommonJS#4083
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The CJS bundle was identical to the ESM bundle because the Rollup config
did not specify `format: 'cjs'`. This caused `require("prismjs")` to
throw a SyntaxError on Node 18–21, and return an unexpected ESM namespace
object on Node 22+.
- Add `format: 'cjs'` to the CJS output options
- Add `format: 'es'` to the ESM output options for clarity
- Write `dist/cjs/package.json` with `{"type":"commonjs"}` so Node
parses the CJS files correctly despite the root `"type": "module"`
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Add a Rollup plugin that appends a one-liner to CJS chunks with mixed
default + named exports, making module.exports the default with named
exports as properties (the Axios pattern). Without this, CJS consumers
would need require("prismjs").default.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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LeaVerou
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Jun 2, 2026
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Summary
dist/cjs/) was byte-for-byte identical to the ESM bundle because the Rollup config never specifiedformat: 'cjs'— both bundles used the default'es'formatrequire("prismjs")to throwSyntaxErroron Node 18–21 (can'trequireESM), and return an unexpected ESM namespace object on Node 22+ (need.defaultto get the Prism instance)format: 'cjs'to the CJS output options so Rollup emitsrequire()/exportssyntaxformat: 'es'to the ESM output options for claritydist/cjs/package.jsonwith{"type":"commonjs"}after the build — needed because the root"type": "module"would otherwise make Node parse the CJS.jsfiles as ESM. Node uses the nearest parentpackage.jsonto determine the module systemcjsExportPluginsorequire("prismjs")returns the Prism instance directly with named exports (Prism,Token,loadLanguages) as properties — no.defaultneeded.Test plan
npm run buildcompletes without errorsnpm testpasses (all 7 suites)npm pack→ install in a fresh project →require("prismjs").highlight(...)works (no.default)require("prismjs").Token,.Prism,.loadLanguagesdist/cjs/index.jscontainsrequire()/exports(notimport/export)dist/cjs/package.jsonexists with{"type":"commonjs"}import Prism from "prismjs") still works🤖 Generated with Claude Code