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SimenB · 2026-05-01T09:18:00Z

Summary

Building on #16063 we can now finally support require(esm) 🎉

Test plan

Tests added

netlify · 2026-05-01T09:18:05Z

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Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds Jest runtime support for Node’s require(esm) behavior (Node v24.9+), including surfacing Node-compatible error codes and exposing loaded ESM modules via require.cache.

Changes:

Implement synchronous require() of ESM modules (Node v24.9+), throwing ERR_REQUIRE_ASYNC_MODULE for async edges (e.g., TLA, async mock factories).
Extend require.cache to include ESM entries (module-shaped wrappers exposing exports as the namespace) with stable identity across reads.
Add unit + e2e coverage and document the new behavior (including Node version gating).

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/jest-runtime/src/index.ts	Core implementation of `require(esm)` sync path, Node-like error codes, and `require.cache` ESM exposure.
packages/jest-runtime/src/tests/test_esm_sync_graph_root/read-require-cache.cjs	Test helper to read `require.cache` from inside a CJS module context.
packages/jest-runtime/src/tests/test_esm_sync_graph_root/import-data-uri-tla.mjs	Fixture ensuring TLA inside `data:` deps surfaces `ERR_REQUIRE_ASYNC_MODULE`.
packages/jest-runtime/src/tests/runtime_esm_sync_graph.test.ts	Unit tests covering `require(esm)` behavior, error surfacing, cache identity, and mocking semantics.
e2e/native-esm/tests/native-esm.test.js	Removes prior expectation that `require(esm)` always throws `ERR_REQUIRE_ESM`.
e2e/native-esm-require-module/package.json	New e2e project config for exercising `require(esm)` in Node environment.
e2e/native-esm-require-module/esm.mjs	E2E ESM fixture for namespace return + default export behavior.
e2e/native-esm-require-module/esm-with-tla.mjs	E2E ESM fixture for TLA → `ERR_REQUIRE_ASYNC_MODULE`.
e2e/native-esm-require-module/tests/require-esm.test.js	E2E tests for successful `require(esm)` behavior and `require.cache` exposure.
e2e/native-esm-require-module/tests/require-esm-throws-on-old-node.test.js	E2E test asserting old-Node gating throws `ERR_REQUIRE_ESM` with version hint.
e2e/tests/nativeEsmRequireModule.test.ts	Harness running the new e2e project on version-gated Node ranges.
e2e/tests/snapshots/nativeEsm.test.ts.snap	Snapshot update due to removed native-esm test.
docs/ECMAScriptModules.md	Documentation for `require()` of ESM (Node v24.9+), errors, and mocking semantics.
CHANGELOG.md	Changelog entry announcing `require()` support for ESM on Node v24.9+.

pkg-pr-new · 2026-05-01T09:37:00Z

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commit: dc31ec6

jmuransky · 2026-05-01T10:07:27Z

Nice! I will have a look at this now. Thank you

jmuransky

Everything else looks fine. Though the support is still not enough for me. Funnily the error I am getting is probably from nodejs:

Cannot require() ES Module FILE synchronously: it is currently being loaded by a concurrent import(). Await that import before calling require(), or import this module instead of requiring it.

I'll try to do minimal repro I can publish and see if there's anything to do about it

SimenB · 2026-05-01T10:51:05Z

I'll try to do minimal repro I can publish and see if there's anything to do about it

Awesome, thanks! I'll happily take a look 🙂

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 4 comments.

Co-authored-by: Copilot <[email protected]>

jmuransky · 2026-05-01T15:11:39Z

@@ -1713,12 +1821,23 @@ export default class Runtime {
    }

    if (this.unstable_shouldLoadAsEsm(modulePath)) {


Just thinking about this.
Do we maybe want to handle case, where this function identifies code as cjs (using .js and package.json does not have type:"module"), but is actually esm? I mean in a manner of try/catch-ing loading the cjs module. I haven't experienced this issue in my repo, but I think I saw packages like that before (dual esm/cjs published code).
Than again I may misremember some details, so think about if this actually makes sense

That's

jest/packages/jest-runtime/src/index.ts

Lines 1675 to 1684 in 572dbae

// The file may contain ESM syntax with no ESM marker (.mjs /

// "type":"module") - try loading as native ESM. If the ESM parser also

// rejects it, the original CJS error was the genuine one; surface it

// instead of the (less useful) ESM diagnostic.

const cjsSyntaxError = error as Error;

return this.loadEsmModule(modulePath).catch(esmError => {

throw isError(esmError) && esmError.name === 'SyntaxError'

? cjsSyntaxError

: esmError;

});

, no? Or am I misunderstanding?

That's probably why I thought about this.

Well I tried to write fixture to test this case and it failed. I'll have a better look at this and see if I did it wrong or if I found a case where it does not apply

Ah no, you meant the other way.

#16078 🙂

SimenB · 2026-05-07T19:08:10Z

https://github.com/jestjs/jest/releases/tag/v30.4.0

| datasource | package | from | to | | ---------- | ------- | ------ | ------ | | npm | jest | 30.3.0 | 30.4.0 | ## [v30.4.0](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3040) ##### Features - `[babel-jest]` Support collecting coverage from `.mts`, `.cts` (and other) files ([#15994](jestjs/jest#15994)) - `[jest-circus, jest-cli, jest-config, jest-core, jest-jasmine2, jest-types]` Add `--collect-tests` flag to discover and list tests without executing them ([#16006](jestjs/jest#16006)) - `[jest-config, jest-runner, jest-worker]` Add `workerGracefulExitTimeout` config option to control how long workers are given to exit before being force-killed ([#15984](jestjs/jest#15984)) - `[jest-config]` Add support for `jest.config.mts` as a valid configuration file ([#16005](jestjs/jest#16005)) - `[jest-config, jest-core, jest-reporters, jest-runner]` `verbose` and `silent` can now be set per-project; the project-level value overrides the global value for that project's tests ([#16133](jestjs/jest#16133)) - `[@jest/fake-timers]` Accept `Temporal.Duration` in `jest.advanceTimersByTime()` and `jest.advanceTimersByTimeAsync()` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Accept `Temporal.Instant` and `Temporal.ZonedDateTime` in `jest.setSystemTime()` and `useFakeTimers({now})` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Support faking `Temporal.Now.*` ([#16131](jestjs/jest#16131)) - `[jest-mock]` Add `clearMocksOnScope(scope)` on `ModuleMocker` for clearing every mock function exposed on a scope object ([#16088](jestjs/jest#16088)) - `[jest-resolve]` Add `canResolveSync()` on `Resolver` so callers can detect when a user-configured resolver only exports an `async` hook ([#16064](jestjs/jest#16064)) - `[jest-runtime]` Use synchronous `evaluate()` for ES modules without top-level `await` on Node versions that support it (v24.9+), and prefer the synchronous transform path when a sync transformer is configured ([#16062](jestjs/jest#16062)) - `[jest-runtime]` Support `require()` of ES modules on Node v24.9+ ([#16074](jestjs/jest#16074)) - `[jest-runtime]` Validate TC39 import attributes (`with { type: 'json' }`) on ESM imports ([#16127](jestjs/jest#16127)) - `[@jest/transform]` Add `canTransformSync(filename)` on `ScriptTransformer` so callers can pick the sync vs async transform path ([#16062](jestjs/jest#16062)) - `[jest-util]` Add `isError` helper ([#16076](jestjs/jest#16076)) - `[pretty-format]` Support React 19 ([#16123](jestjs/jest#16123)) ##### Fixes - `[expect-utils]` Fix `toStrictEqual` failing on `structuredClone` results due to cross-realm constructor mismatch ([#15959](jestjs/jest#15959)) - `[@jest/expect-utils]` Prevent `toMatchObject`/subset matching from throwing when encountering exotic iterables ([#15952](jestjs/jest#15952)) - `[fake-timers]` Convert `Date` to milliseconds before passing to `@sinonjs/fake-timers` ([#16029](jestjs/jest#16029)) - `[jest]` Export `GlobalConfig` and `ProjectConfig` TypeScript types ([#16132](jestjs/jest#16132)) - `[jest-circus]` Prevent crash when `asyncError` is undefined for non-Error throws ([#16003](jestjs/jest#16003)) - `[jest-circus, jest-jasmine2]` Include `Error.cause` in JSON `failureMessages` output ([#15967](jestjs/jest#15967)) - `[jest-config]` Fix preset path resolution on Windows when the preset uses subpath `exports` ([#15961](jestjs/jest#15961)) - `[jest-config]` Allow `collectCoverage` and `coverageProvider` in project config without a validation warning ([#16132](jestjs/jest#16132)) - `[jest-config]` Project config validator now emits "is not supported in an individual project configuration" instead of "probably a typing mistake" for known global-only options ([#16132](jestjs/jest#16132)) - `[jest-environment-node]` Fix `--localstorage-file` warning on Node 25+ ([#16086](jestjs/jest#16086)) - `[jest-reporters]` Apply global coverage threshold to unmatched pattern files in addition to glob/path thresholds ([#16137](jestjs/jest#16137)) - `[jest-reporters, jest-runner, jest-runtime, jest-transform]` Fix coverage report not showing correct code coverage when using `projects` config option ([#16140](jestjs/jest#16140)) - `[jest-runtime]` Resolve `expect` and `@jest/expect` from the internal module registry so test-file imports share the same `JestAssertionError` as the global `expect` ([#16130](jestjs/jest#16130)) - `[jest-runtime]` Improve CJS-from-ESM interop: `__esModule`/Babel default unwrap, broader named-export coverage, and shared CJS singleton across importers ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Load `.js` files with ESM syntax but no `"type":"module"` marker as native ESM ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Extend the `.js`-with-ESM-syntax fallback to `require()` on Node v24.9+ - falls back to `require(esm)` when the CJS parser rejects ESM syntax ([#16078](jestjs/jest#16078)) - `[jest-runtime]` Fix deadlocks and double-evaluation in concurrent ESM and wasm imports ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Fix error when `require()` is called after the Jest environment has been torn down ([#15951](jestjs/jest#15951)) - `[jest-runtime]` Fix missing error when `import()` is called after the Jest environment has been torn down ([#16080](jestjs/jest#16080)) - `[jest-runtime]` Fix virtual `unstable_mockModule` registrations not respected in ESM ([#16081](jestjs/jest#16081)) - `[jest-runtime]` Apply `moduleNameMapper` when resolving modules with `require.resolve()` and the `paths` option ([#16135](jestjs/jest#16135)) ##### Chore & Maintenance - `[@jest/fake-timers]` Upgrade `@sinonjs/fake-timers` ([#16139](jestjs/jest#16139)) - `[jest-runtime]` Use synchronous `linkRequests` / `instantiate` for ESM linking on Node v24.9+ ([#16063](jestjs/jest#16063))

| datasource | package | from | to | | ---------- | ------- | ------ | ------ | | npm | jest | 30.3.0 | 30.4.2 | ## [v30.4.2](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3042) ##### Fixes - `[jest-runtime]` Fix named imports from CJS modules whose `module.exports` is a function with own-property exports ([#16150](jestjs/jest#16150)) ## [v30.4.1](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3041) ##### Features - `[jest-config, jest-core, jest-runner, jest-schemas, jest-types]` Allow custom runner configuration options via tuple format `['runner-path', {options}]` ([#16141](jestjs/jest#16141)) ##### Fixes - `[jest-runtime]` Align CJS-from-ESM default export with Node: `module.exports` is always the ESM default, `__esModule` unwrapping is no longer applied ([#16143](jestjs/jest#16143)) ## [v30.4.0](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md#3040) ##### Features - `[babel-jest]` Support collecting coverage from `.mts`, `.cts` (and other) files ([#15994](jestjs/jest#15994)) - `[jest-circus, jest-cli, jest-config, jest-core, jest-jasmine2, jest-types]` Add `--collect-tests` flag to discover and list tests without executing them ([#16006](jestjs/jest#16006)) - `[jest-config, jest-runner, jest-worker]` Add `workerGracefulExitTimeout` config option to control how long workers are given to exit before being force-killed ([#15984](jestjs/jest#15984)) - `[jest-config]` Add support for `jest.config.mts` as a valid configuration file ([#16005](jestjs/jest#16005)) - `[jest-config, jest-core, jest-reporters, jest-runner]` `verbose` and `silent` can now be set per-project; the project-level value overrides the global value for that project's tests ([#16133](jestjs/jest#16133)) - `[@jest/fake-timers]` Accept `Temporal.Duration` in `jest.advanceTimersByTime()` and `jest.advanceTimersByTimeAsync()` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Accept `Temporal.Instant` and `Temporal.ZonedDateTime` in `jest.setSystemTime()` and `useFakeTimers({now})` ([#16128](jestjs/jest#16128)) - `[@jest/fake-timers]` Support faking `Temporal.Now.*` ([#16131](jestjs/jest#16131)) - `[jest-mock]` Add `clearMocksOnScope(scope)` on `ModuleMocker` for clearing every mock function exposed on a scope object ([#16088](jestjs/jest#16088)) - `[jest-resolve]` Add `canResolveSync()` on `Resolver` so callers can detect when a user-configured resolver only exports an `async` hook ([#16064](jestjs/jest#16064)) - `[jest-runtime]` Use synchronous `evaluate()` for ES modules without top-level `await` on Node versions that support it (v24.9+), and prefer the synchronous transform path when a sync transformer is configured ([#16062](jestjs/jest#16062)) - `[jest-runtime]` Support `require()` of ES modules on Node v24.9+ ([#16074](jestjs/jest#16074)) - `[jest-runtime]` Validate TC39 import attributes (`with { type: 'json' }`) on ESM imports ([#16127](jestjs/jest#16127)) - `[@jest/transform]` Add `canTransformSync(filename)` on `ScriptTransformer` so callers can pick the sync vs async transform path ([#16062](jestjs/jest#16062)) - `[jest-util]` Add `isError` helper ([#16076](jestjs/jest#16076)) - `[pretty-format]` Support React 19 ([#16123](jestjs/jest#16123)) ##### Fixes - `[expect-utils]` Fix `toStrictEqual` failing on `structuredClone` results due to cross-realm constructor mismatch ([#15959](jestjs/jest#15959)) - `[@jest/expect-utils]` Prevent `toMatchObject`/subset matching from throwing when encountering exotic iterables ([#15952](jestjs/jest#15952)) - `[fake-timers]` Convert `Date` to milliseconds before passing to `@sinonjs/fake-timers` ([#16029](jestjs/jest#16029)) - `[jest]` Export `GlobalConfig` and `ProjectConfig` TypeScript types ([#16132](jestjs/jest#16132)) - `[jest-circus]` Prevent crash when `asyncError` is undefined for non-Error throws ([#16003](jestjs/jest#16003)) - `[jest-circus, jest-jasmine2]` Include `Error.cause` in JSON `failureMessages` output ([#15967](jestjs/jest#15967)) - `[jest-config]` Fix preset path resolution on Windows when the preset uses subpath `exports` ([#15961](jestjs/jest#15961)) - `[jest-config]` Allow `collectCoverage` and `coverageProvider` in project config without a validation warning ([#16132](jestjs/jest#16132)) - `[jest-config]` Project config validator now emits "is not supported in an individual project configuration" instead of "probably a typing mistake" for known global-only options ([#16132](jestjs/jest#16132)) - `[jest-environment-node]` Fix `--localstorage-file` warning on Node 25+ ([#16086](jestjs/jest#16086)) - `[jest-reporters]` Apply global coverage threshold to unmatched pattern files in addition to glob/path thresholds ([#16137](jestjs/jest#16137)) - `[jest-reporters, jest-runner, jest-runtime, jest-transform]` Fix coverage report not showing correct code coverage when using `projects` config option ([#16140](jestjs/jest#16140)) - `[jest-runtime]` Resolve `expect` and `@jest/expect` from the internal module registry so test-file imports share the same `JestAssertionError` as the global `expect` ([#16130](jestjs/jest#16130)) - `[jest-runtime]` Improve CJS-from-ESM interop: `__esModule`/Babel default unwrap, broader named-export coverage, and shared CJS singleton across importers ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Load `.js` files with ESM syntax but no `"type":"module"` marker as native ESM ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Extend the `.js`-with-ESM-syntax fallback to `require()` on Node v24.9+ - falls back to `require(esm)` when the CJS parser rejects ESM syntax ([#16078](jestjs/jest#16078)) - `[jest-runtime]` Fix deadlocks and double-evaluation in concurrent ESM and wasm imports ([#16050](jestjs/jest#16050)) - `[jest-runtime]` Fix error when `require()` is called after the Jest environment has been torn down ([#15951](jestjs/jest#15951)) - `[jest-runtime]` Fix missing error when `import()` is called after the Jest environment has been torn down ([#16080](jestjs/jest#16080)) - `[jest-runtime]` Fix virtual `unstable_mockModule` registrations not respected in ESM ([#16081](jestjs/jest#16081)) - `[jest-runtime]` Apply `moduleNameMapper` when resolving modules with `require.resolve()` and the `paths` option ([#16135](jestjs/jest#16135)) ##### Chore & Maintenance - `[@jest/fake-timers]` Upgrade `@sinonjs/fake-timers` ([#16139](jestjs/jest#16139)) - `[jest-runtime]` Use synchronous `linkRequests` / `instantiate` for ESM linking on Node v24.9+ ([#16063](jestjs/jest#16063))

upgrade jest dependencies https://github.com/jestjs/jest/blob/main/CHANGELOG.md#3040 allows us to remove override from react-is see jestjs/jest#16123 require(esm) is neat jestjs/jest#16074

feat: support require(esm)

fdbdc84

Copilot AI review requested due to automatic review settings May 1, 2026 09:18

changelog link

9d81b91

SimenB mentioned this pull request May 1, 2026

Better ESM-CJS compatibility fix #16050

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[Feature]: Support require of pure ESM packages #15275

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Proposal: new vm module primitives & loader API for ESM customization nodejs/node#62720

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SimenB force-pushed the require-esm branch from 26db649 to c4ece5d Compare May 1, 2026 10:15

tweaks

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chill on the comments

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fix typo

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add more tests (and fix minor bug)

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nah

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more minor cleanups

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synchronously evaluate synthetic modules

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Merge branch 'main' into require-esm

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less noise

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assert the invariance

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[Feature]: Support require of pure ESM packages #15275

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SimenB and others added 3 commits May 1, 2026 15:26

clear new cache as well

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Update e2e/__tests__/nativeEsmSyncLinker.test.ts

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sync evaluate is only on newer nodes

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fix: fall back to require(esm) when CJS parses .js with ESM syntax #16078

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ST-DDT mentioned this pull request May 4, 2026

Faker v10 ESM-only breaks compatibility with Jest faker-js/faker#3606

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scttcper mentioned this pull request May 18, 2026

deps(ui): Upgrade jest to 30.4 getsentry/sentry#115725

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		@@ -1713,12 +1821,23 @@ export default class Runtime {
		}

		if (this.unstable_shouldLoadAsEsm(modulePath)) {

	// The file may contain ESM syntax with no ESM marker (.mjs /
	// "type":"module") - try loading as native ESM. If the ESM parser also
	// rejects it, the original CJS error was the genuine one; surface it
	// instead of the (less useful) ESM diagnostic.
	const cjsSyntaxError = error as Error;
	return this.loadEsmModule(modulePath).catch(esmError => {
	throw isError(esmError) && esmError.name === 'SyntaxError'
	? cjsSyntaxError
	: esmError;
	});

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SimenB commented May 1, 2026

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SimenB commented May 7, 2026

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netlify Bot commented May 1, 2026 •

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