feat!: migrate to esm-only by kettanaito · Pull Request #2765 · mswjs/msw

kettanaito · 2026-07-18T16:06:50Z

Migrates MSW to be ESM-only 🎉 Finally.

coderabbitai · 2026-07-18T16:07:09Z

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socket-security · 2026-07-18T16:09:50Z

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Package	Supply Chain Security	Quality
@commitlint/cli@21.2.1
@types/serviceworker@0.0.199
@fastify/websocket@11.3.0
tsdown@0.22.9
tough-cookie@6.0.2
oxlint@1.73.0 ⏵ 1.74.0	⁺¹	⁺¹
knip@6.27.0
@commitlint/config-conventional@21.2.0
prettier@3.9.5
lint-staged@17.1.0

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pkg-pr-new · 2026-07-18T16:13:33Z

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npm i https://pkg.pr.new/msw@2765

commit: dabe4b3

coderabbitai

Actionable comments posted: 2

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Verify each finding against current code. Fix only still-valid issues, skip the
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Inline comments:
In `@config/plugins/rolldown/forceFileExtensionsPlugin.ts`:
- Around line 21-35: Update ESM_RELATIVE_IMPORT_EXP and modifyRelativeImports to
rewrite both from-clause and side-effect relative imports, while preserving
existing non-JavaScript extensions such as .json instead of appending
ESM_EXTENSION. Retain directory handling with /index and support
import-attribute syntax, then add coverage for side-effect, JSON, directory, and
import-attribute cases before publishing chunks.

In `@config/plugins/rolldown/resolveCoreImportsPlugin.ts`:
- Around line 3-31: Update resolveCoreImportsPlugin and replaceCoreImports so
the rewritten `#core` import path is calculated relative to each emitted chunk’s
fileName rather than hardcoding ../core. Pass the chunk fileName into the
replacement logic and preserve the existing submodule and semicolon handling
while resolving the correct relative path for nested output chunks.

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Reviewing files that changed from the base of the PR and between 5283bf7 and dabe4b3.

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📒 Files selected for processing (20)

.oxlintrc.json
browser/package.json
cli/package.json
commitlint.config.js
config/package.json
config/plugins/rolldown/copyWorkerPlugin.ts
config/plugins/rolldown/forceFileExtensionsPlugin.ts
config/plugins/rolldown/resolveCoreImportsPlugin.ts
config/replaceCoreImports.js
config/scripts/patch-ts.js
config/scripts/postinstall.js
graphql/package.json
native/package.json
node/package.json
package.json
src/package.json
test/modules/node/esm-node.test.ts
test/support/alias.ts
test/support/msw-esm/package.json
tsdown.config.mts

💤 Files with no reviewable changes (10)

config/replaceCoreImports.js
node/package.json
cli/package.json
src/package.json
config/scripts/patch-ts.js
browser/package.json
graphql/package.json
config/package.json
native/package.json
test/support/msw-esm/package.json

@kettanaito

##### [v3.0.2](https://github.com/mswjs/msw/releases/tag/v3.0.2) #### v3.0.2 (2026-10-03) ##### Bug Fixes - **vite:** support `virtual:msw` imports in vitest ([#2802](mswjs/msw#2802)) ([`e73c381`](mswjs/msw@e73c381)) [@kettanaito](https://github.com/kettanaito) ##### [v3.0.1](https://github.com/mswjs/msw/releases/tag/v3.0.1) #### v3.0.1 (2026-09-30) ##### Bug Fixes - treat `CONNECT` requests as the transport mechanism ([#2796](mswjs/msw#2796)) ([`7cad86a`](mswjs/msw@7cad86a)) [@kettanaito](https://github.com/kettanaito) ##### [v3.0.0](https://github.com/mswjs/msw/releases/tag/v3.0.0) #### v3.0.0 (2026-09-28) - v3.0.0 ([#2692](mswjs/msw#2692)) ([`2bb4342`](mswjs/msw@2bb4342)) [@kettanaito](https://github.com/kettanaito) [@Andarist](https://github.com/Andarist) ##### ⚠️ BREAKING CHANGES - **MSW is now ESM-only** ([#2765](mswjs/msw#2765)). - Deprecate support for Node.js v18 and v20 ([#2729](mswjs/msw#2729)). The minimal supported Node.js version is v22. - `msw/native` is removed in favor of [`@msw/react-native`](https://github.com/mswjs/react-native). - Require TypeScript 5.9 as the minimal version. - Deprecate support for TypeScript 5.1 and 5.2 ([#2730](mswjs/msw#2730)) - `worker.stop()` returns a Promise ([#2724](mswjs/msw#2724)). Awaiting it is relevant only for in-flight critical scenarios. - `graphql` is now exported as `msw/graphql` ([#2691](mswjs/msw#2691)). GraphQL is now handled as a proper optional peer dependency. - Removes the `handleRequest()` utility. Please use the `defineNetwork()` API instead. - `GraphQLLinkHandlers` type has been renamed to `GraphQLLink`. - The `file://` requests now throw in Node.js as they normally do (not supported by `fetch`). - The `Content-Length` request header is now removed by `bypass()`. - HTTP-to-WebSocket upgrade requests performed via `fetch()` now throw in Node.js as they normally do (not supported by `fetch`). - Cookies are no longer managed in Node.js for better compatibilty. Instead, whatever is the default behavior of your environment that's the cookie behavior you get. This has no effect on the browser. - WebSocket `connection` life cycle event has been renamed to `websocket:connection` ([#2783](mswjs/msw#2783)). - `onUnhandledRequest` option has been renamed to `onUnhandledFrame`. - The library no longer patches `setTimeout` to circumvent fake timers in test runners. You should advance the fake timers normally for delayed mocked responses to resolve. - The library no longer returns a mocked cookie string on `request.headers.get('cookie')` in the handlers. It returns `null` in all environments. Please use the `cookies` resolver argument to have cookie-based logic. ##### Features - Supports Node.js v24 and v26. - Supports TypeScript v6.0 and v7.0. - You can import individual utilities, like `delay` or `passthrough`, from the new `msw/utils` entrypoint for smaller footprint on your bundle. - Support GraphQL v17.0. - Support intercepting page navigations and form submissions ([#2721](mswjs/msw#2721)). - Support GraphQL subscriptions ([#285](mswjs/msw#285), [#2763](mswjs/msw#2763)). - Migrate from `path-to-regexp` to `@msw/url` ([#2678](mswjs/msw#2678)). - Remove the following dependencies: - `graphql` - `path-to-regexp` - `picocolors` - `statuses` - `strict-event-emitter` - Adds a Vite plugin for MSW ([#2781](mswjs/msw#2781)). - Adds a `websocket:error` life cycle event to listen to WebSocket connection errors ([#2784](mswjs/msw#2784)). - Support modifying the intercepted request headers in passthrough scenarios ([#2786](mswjs/msw#2786)). - Support a new WebSocket Extension API that allows for better custom experiences ([#2791](mswjs/msw#2791)). ##### Bug fixes - Fix an issue where preventing a page closure via the `beforeunload` listener would unregister the MSW worker ([#1105](mswjs/msw#1105)). - Fix an issue that caused intermittent test failures in Vitest Browser Mode and Firefox if using `maxWorkers: 1` ([#2726](mswjs/msw#2726)). - Fix an issue where in-flight requests were incorrectly passthrough when performed before calling `worker.stop()` ([#2724](mswjs/msw#2724), [#2597](mswjs/msw#2597)). - Fix an issue where persisting cookies in `localStorage` would cause a maximum quota exceeded errors. - Fix various issues related to the network interception in Node.js.

@kettanaito

##### [v3.0.3](https://github.com/mswjs/msw/releases/tag/v3.0.3) #### v3.0.3 (2026-10-10) ##### Bug Fixes - **HandlersController:** dispose of reset handlers ([#2810](mswjs/msw#2810)) ([`3818a81`](mswjs/msw@3818a81)) [@kettanaito](https://github.com/kettanaito) - expose network context on `enable` in network sources ([#2809](mswjs/msw#2809)) ([`d1fe8e6`](mswjs/msw@d1fe8e6)) [@kettanaito](https://github.com/kettanaito) ##### [v3.0.2](https://github.com/mswjs/msw/releases/tag/v3.0.2) #### v3.0.2 (2026-10-03) ##### Bug Fixes - **vite:** support `virtual:msw` imports in vitest ([#2802](mswjs/msw#2802)) ([`e73c381`](mswjs/msw@e73c381)) [@kettanaito](https://github.com/kettanaito) ##### [v3.0.1](https://github.com/mswjs/msw/releases/tag/v3.0.1) #### v3.0.1 (2026-09-30) ##### Bug Fixes - treat `CONNECT` requests as the transport mechanism ([#2796](mswjs/msw#2796)) ([`7cad86a`](mswjs/msw@7cad86a)) [@kettanaito](https://github.com/kettanaito) ##### [v3.0.0](https://github.com/mswjs/msw/releases/tag/v3.0.0) #### v3.0.0 (2026-09-28) - v3.0.0 ([#2692](mswjs/msw#2692)) ([`2bb4342`](mswjs/msw@2bb4342)) [@kettanaito](https://github.com/kettanaito) [@Andarist](https://github.com/Andarist) ##### ⚠️ BREAKING CHANGES - **MSW is now ESM-only** ([#2765](mswjs/msw#2765)). - Deprecate support for Node.js v18 and v20 ([#2729](mswjs/msw#2729)). The minimal supported Node.js version is v22. - `msw/native` is removed in favor of [`@msw/react-native`](https://github.com/mswjs/react-native). - Require TypeScript 5.9 as the minimal version. - Deprecate support for TypeScript 5.1 and 5.2 ([#2730](mswjs/msw#2730)) - `worker.stop()` returns a Promise ([#2724](mswjs/msw#2724)). Awaiting it is relevant only for in-flight critical scenarios. - `graphql` is now exported as `msw/graphql` ([#2691](mswjs/msw#2691)). GraphQL is now handled as a proper optional peer dependency. - Removes the `handleRequest()` utility. Please use the `defineNetwork()` API instead. - `GraphQLLinkHandlers` type has been renamed to `GraphQLLink`. - The `file://` requests now throw in Node.js as they normally do (not supported by `fetch`). - The `Content-Length` request header is now removed by `bypass()`. - HTTP-to-WebSocket upgrade requests performed via `fetch()` now throw in Node.js as they normally do (not supported by `fetch`). - Cookies are no longer managed in Node.js for better compatibility. Instead, whatever is the default behavior of your environment that's the cookie behavior you get. This has no effect on the browser. - WebSocket `connection` life cycle event has been renamed to `websocket:connection` ([#2783](mswjs/msw#2783)). - `onUnhandledRequest` option has been renamed to `onUnhandledFrame`. - The library no longer patches `setTimeout` to circumvent fake timers in test runners. You should advance the fake timers normally for delayed mocked responses to resolve. - The library no longer returns a mocked cookie string on `request.headers.get('cookie')` in the handlers. It returns `null` in all environments. Please use the `cookies` resolver argument to have cookie-based logic. ##### Features - Supports Node.js v24 and v26. - Supports TypeScript v6.0 and v7.0. - You can import individual utilities, like `delay` or `passthrough`, from the new `msw/utils` entrypoint for smaller footprint on your bundle. - Support GraphQL v17.0. - Support intercepting page navigations and form submissions ([#2721](mswjs/msw#2721)). - Support GraphQL subscriptions ([#285](mswjs/msw#285), [#2763](mswjs/msw#2763)). - Migrate from `path-to-regexp` to `@msw/url` ([#2678](mswjs/msw#2678)). - Remove the following dependencies: - `graphql` - `path-to-regexp` - `picocolors` - `statuses` - `strict-event-emitter` - Adds a Vite plugin for MSW ([#2781](mswjs/msw#2781)). - Adds a `websocket:error` life cycle event to listen to WebSocket connection errors ([#2784](mswjs/msw#2784)). - Support modifying the intercepted request headers in passthrough scenarios ([#2786](mswjs/msw#2786)). - Support a new WebSocket Extension API that allows for better custom experiences ([#2791](mswjs/msw#2791)). ##### Bug fixes - Fix an issue where preventing a page closure via the `beforeunload` listener would unregister the MSW worker ([#1105](mswjs/msw#1105)). - Fix an issue that caused intermittent test failures in Vitest Browser Mode and Firefox if using `maxWorkers: 1` ([#2726](mswjs/msw#2726)). - Fix an issue where in-flight requests were incorrectly passthrough when performed before calling `worker.stop()` ([#2724](mswjs/msw#2724), [#2597](mswjs/msw#2597)). - Fix an issue where persisting cookies in `localStorage` would cause a maximum quota exceeded errors. - Fix various issues related to the network interception in Node.js.

kettanaito added 2 commits July 18, 2026 18:01

feat: migrate to esm-only

99d76b7

chore: remove unnecessary scripts

986488b

chore: update dependencies

7462f6d

fix: put types export condition first

dabe4b3

kettanaito mentioned this pull request Jul 18, 2026

feat!: v3.0.0 #2692

Merged

37 tasks done

coderabbitai Bot reviewed Jul 18, 2026

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Comment thread config/plugins/rolldown/forceFileExtensionsPlugin.ts

Comment thread config/plugins/rolldown/resolveCoreImportsPlugin.ts

chore: resolve core imports from chunks

eabc934

kettanaito merged commit be2ae7c into feat/3.0 Jul 18, 2026
21 checks passed

kettanaito deleted the feat/esm-only branch July 18, 2026 16:30

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feat!: migrate to esm-only - #2765

feat!: migrate to esm-only#2765
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