module: enable existing machinery for deferred imports by MayaLekova · Pull Request #63712 · nodejs/node

MayaLekova · 2026-06-02T14:17:18Z

This commit enables deferred module imports by using the corresponding functionality in V8. It also adds a single test, but more test coverage should be added.

Refs: https://github.com/tc39/proposal-defer-import-eval

nodejs-github-bot · 2026-06-02T14:17:25Z

Review requested:

@nodejs/loaders
@nodejs/vm

joyeecheung

I think the commit message needs to clarify that this only makes it work for static import, but not dynamic import yet?

codecov · 2026-06-02T15:55:13Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.35%. Comparing base (6813080) to head (6bb2db9).
⚠️ Report is 24 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #63712    +/-   ##
========================================
  Coverage   90.34%   90.35%            
========================================
  Files         732      732            
  Lines      236580   236709   +129     
  Branches    44545    44585    +40     
========================================
+ Hits       213748   213870   +122     
- Misses      14536    14565    +29     
+ Partials     8296     8274    -22

Files with missing lines	Coverage Δ
src/module_wrap.cc	`74.41% <100.00%> (+0.04%)`	⬆️
src/module_wrap.h	`52.94% <ø> (ø)`

... and 53 files with indirect coverage changes

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MayaLekova · 2026-06-03T12:59:24Z

Thank you, I moved the test, but should I add more extensive test coverage, even for static imports?

joyeecheung · 2026-06-04T12:58:54Z

I think a smoke test is enough. The rest should be covered by test262 in the upstream.

Can you rewrap the commit message to 72 chars to make the linter happy? Also this needs adding a eslint plugin

2026-06-03T13:01:48.8039114Z /home/runner/work/node/node/test/es-module/test-defer-import-eval.mjs
2026-06-03T13:01:48.8044324Z 10:7 error Parsing error: This experimental syntax requires enabling the parser plugin: "deferredImportEvaluation". (10:7)

mcollina

Amazing!

guybedford

Works perfectly thank you!

nodejs-github-bot · 2026-06-09T21:08:33Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74006/

MayaLekova · 2026-06-10T14:31:11Z

Thanks for the reviews! Do you mind checking the updated version? (minor changes in tests only)
@joyeecheung @guybedford

guybedford

Test looks good. It would be great to see a Wasm test too (import defer * as foo from './foo.wasm'), but that also isn't necessary either.

nodejs-github-bot · 2026-06-10T22:06:17Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74046/

This commit enables deferred import for statically imported modules, by using the corresponding functionality in V8. It adds two tests: - smoke test exercising the basic syntax - test for deferred import of module with its own imports More test coverage should be added for mixing ESM and CJS modules, as well as TypeScript modules. Refs: https://github.com/tc39/proposal-defer-import-eval Signed-off-by: Maya Lekova <maya@igalia.com>

nodejs-github-bot · 2026-06-13T23:21:55Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74108/

nodejs-github-bot · 2026-06-14T07:50:00Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74110/

nodejs-github-bot · 2026-06-14T19:00:28Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74134/

nodejs-github-bot · 2026-06-16T15:37:33Z

CI: https://ci.nodejs.org/job/node-test-pull-request/74185/

nodejs-github-bot · 2026-06-16T20:39:23Z

Landed in b09155d

MayaLekova · 2026-06-16T23:47:41Z

Test looks good. It would be great to see a Wasm test too (import defer * as foo from './foo.wasm'), but that also isn't necessary either.

Thank you for helping me land this PR!

I'll add more tests in the next commits, including some with Wasm modules.

This commit enables deferred import for statically imported modules, by using the corresponding functionality in V8. It adds two tests: - smoke test exercising the basic syntax - test for deferred import of module with its own imports More test coverage should be added for mixing ESM and CJS modules, as well as TypeScript modules. Refs: https://github.com/tc39/proposal-defer-import-eval Signed-off-by: Maya Lekova <maya@igalia.com> PR-URL: #63712 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com> Reviewed-By: Guy Bedford <guybedford@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>

MayaLekova changed the title ~~module: enable existing machinery for import defer~~ module: enable existing machinery for deferred imports Jun 2, 2026

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. needs-ci PRs that need a full CI run. labels Jun 2, 2026

MayaLekova force-pushed the import-defer-01 branch from 0968bc3 to 6bb2db9 Compare June 2, 2026 14:22

joyeecheung reviewed Jun 2, 2026

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Comment thread test/fixtures/es-modules/module-deferred-eval.mjs

MayaLekova force-pushed the import-defer-01 branch from 6bb2db9 to 5e52c9a Compare June 3, 2026 12:56

mcollina approved these changes Jun 5, 2026

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MayaLekova force-pushed the import-defer-01 branch 3 times, most recently from 2915765 to bd9968c Compare June 8, 2026 15:08

guybedford reviewed Jun 8, 2026

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Comment thread src/module_wrap.h

MayaLekova force-pushed the import-defer-01 branch from bd9968c to 569d71c Compare June 9, 2026 16:35

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Comment thread test/es-module/test-defer-import-eval.mjs Outdated

Comment thread test/es-module/test-defer-import-with-module-tree.mjs Outdated

MayaLekova force-pushed the import-defer-01 branch from 569d71c to a519846 Compare June 10, 2026 13:01

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MayaLekova force-pushed the import-defer-01 branch from a519846 to 7b9767e Compare June 12, 2026 14:50

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nodejs-github-bot merged commit b09155d into nodejs:main Jun 16, 2026
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