fix(ext/node): run worker_threads eval code in sloppy mode#32428
Merged
bartlomieju merged 8 commits intomainfrom Mar 10, 2026
Merged
fix(ext/node): run worker_threads eval code in sloppy mode#32428bartlomieju merged 8 commits intomainfrom
bartlomieju merged 8 commits intomainfrom
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Node.js evaluates `{ eval: true }` worker code as CommonJS (sloppy mode),
but Deno was wrapping it in `import` statements and loading it as a
`data:text/javascript` URL via `load_main_es_module`, which enforces
strict mode. This broke libraries like fflate that use bare variable
assignments (e.g. `u8 = Uint8Array`) in their worker code.
The fix passes eval code via `hasSourceCode: true` so it goes through
V8's `execute_script` (sloppy mode) instead of the ES module loader.
Fixes #26739
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The previous commit unconditionally ran eval workers in sloppy mode via execute_script, which broke eval code using import/export syntax. Node.js auto-detects: code with import/export runs as ESM (strict), code without runs as CJS (sloppy). This commit replicates that behavior with a simple regex check for module syntax. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
These tests now pass thanks to the sloppy mode and ESM/CJS auto-detection fixes for worker_threads eval code. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
devsnek
reviewed
Mar 5, 2026
Per review feedback, worker eval code should always run as CJS (sloppy mode) — remove the ESM auto-detection path. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Since eval workers now unconditionally run as CJS, all tests using `import` in eval worker strings need to use `require()` instead. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Remove unused `encodeURIComponent` import (lint failure after
removing the ESM eval path).
- Use `require("node:assert")` instead of `require("${common}")`
in napi init_test worker since `import.meta.resolve()` returns
a file:// URL that `require()` cannot resolve.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
kajukitli
approved these changes
Mar 7, 2026
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kajukitli
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lgtm — good fix for the strict mode vs sloppy mode mismatch
the approach is correct:
- using
hasSourceCode: truewithexecute_scriptruns the code in sloppy mode (V8 script evaluation) - the previous approach with
data:text/javascriptforced ESM (strict mode) - the
vardeclarations for CJS globals are correct sinceconst/letwould be block-scoped
test coverage:
- new
eval_sloppy_mode.mjstest with bare assignment (myGlobal = 42) validates sloppy mode - existing tests updated to use
require()instead ofimportwhich is more accurate to CJS
one thing to note: the PR description mentions fflate may have additional issues with transferred data — might be worth a follow-up issue if that's still broken
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Summary
node:worker_threadswith{ eval: true }was wrapping code inimportstatements and loading it as adata:text/javascriptURL viaload_main_es_module, which enforces strict mode. Node.js runs eval workers as CommonJS (sloppy mode).u8 = Uint8Array) in their serialized worker code fail withReferenceError: u8 is not defined.hasSourceCode: trueso it goes through V8'sexecute_script(sloppy mode) instead of the ES module loader. CJS globals (require) are already provided by the Node worker bootstrap; we just add__filename,__dirname,module, andexportsviavardeclarations.Fixes #26739
Fixes #21695