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CJS output's sourceMappingURL and map file field point at the ESM map name #71
Description
When emitting the CJS build, the .cjs / .d.cts files keep the //# sourceMappingURL= comment from the original TS emit, so they reference *.js.map / *.d.ts.map instead of their own *.cjs.map / *.d.cts.map. The companion map files also carry the wrong "file" field (the .js / .d.ts name).
Because the ESM and CJS maps have different mappings, every CJS consumer — Node --enable-source-maps, source-map-support, ts-node/tsx, Jest/Mocha, IDE "go to definition" — resolves to the wrong map and misreports positions.
Repro
zshy's own published package exhibits it:
$ grep sourceMappingURL node_modules/zshy/dist/index.cjs
//# sourceMappingURL=index.js.map # expected index.cjs.map
$ grep '"file"' node_modules/zshy/dist/index.cjs.map
"file":"index.js" # expected "index.cjs"
Same for .d.cts → .d.ts.map.
Cause
In compile.js, the host.writeFile hook renames the output path (.js→.cjs, etc.) but writes data unmodified, so the in-file sourceMappingURL comment and the map "file" field still reference the original names.
Fix
When renaming, also rewrite the contents — the sourceMappingURL comment in .cjs/.d.cts, and the "file" field in .cjs.map/.d.cts.map.
Version
zshy 0.7.3
Activity
pullfrog commentedon Jun 24, 2026
michi: start colinhacks#71
T1: rewrite sourceMappingURL comment and map file field on rename (co…
T2: add regression test for CJS source map references (colinhacks#71)
T3: regenerate fixtures with corrected CJS source map references (col…
T4: anchor sourceMappingURL rewrite to end-of-file (colinhacks#71)