feat!: v3.0.0

[kettanaito]

• Fixes Support GraphQL subscriptions #285
• Fixes Support intercepting navigate requests #1594
• Fixes My app hooks in beforeunload with a confirmation message and then MSW stops working #1105
• Fixes GraphQL 17 support #2770

BREAKING CHANGES

• MSW is now ESM-only (feat!: migrate to esm-only #2765).
• Deprecate support for Node.js v18 and v20 (feat: drop support for Node.js 18, 20 #2729). The minimal supported Node.js version is v22.
• Require TypeScript 5.9 as the minimal version.
• Deprecate support for TypeScript 5.1 and 5.2 (chore: use Headers.getSetCookie #2730)
• worker.stop() returns a Promise (fix: await in-flight requests from closing clients #2724). Awaiting it is relevant only for in-flight critical scenarios.
• graphql is now exported as msw/graphql (feat!: msw/graphql, graphql as an optional peer dependency #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).

Features

• Support TypeScript 6.0 and 7.0.
• Support GraphQL 17.
• Support intercepting page navigations and form submissions (feat: support navigate requests #2721).
• Support GraphQL subscriptions (Support GraphQL subscriptions #285, feat: support GraphQL subscriptions #2763).
• Migrate from path-to-regexp to @msw/url (feat!: migrate to @msw/url #2678).
• Remove the following dependencies:
  • graphql
  • path-to-regexp
  • picocolors
  • statuses
  • strict-event-emitter

Bug fixes

• Fix an issue where preventing a page closure via the beforeunload listener would unregister the MSW worker (My app hooks in beforeunload with a confirmation message and then MSW stops working #1105).
• Fix an issue that caused intermittent test failures in Vitest Browser Mode and Firefox if using maxWorkers: 1 (Firefox & Vitest Browser Mode Timing Problems (CI) #2726).
• Fix an issue where in-flight requests were incorrectly passthrough when performed before calling worker.stop() (fix: await in-flight requests from closing clients #2724, MSW sometimes still handles requests after worker is stopped #2597).

---

Roadmap

• Migrate to ESM-only.
• msw/ws
• msw/http
• Decide on the root vs explicit export paths import experience. msw/graphql is the only way to consume GraphQL due to optional peer dependency on graphql.
• Consider renaming msw/native to msw/react-native OR consider @msw/react-native altogether to have necessary polyfills, full RN app tests, etc.
• Support Node.js v26.
• Revise defineNetwork and move it out from /experimental.
• Migrate to pnpm@11.
• Support TypeScript up to 7.0 (investigate if 7.0 can be supported, too).
• Consider dropping statuses. That's the only CJS dependency requiring a shim.
• Update graphql version (d9f389d).
• Remove the postinstall hook in favor of explicit msw init (Make worker autoupdate an explicit choice #1297, Issue: postinstall breaks during ci installation #2704).
• Remove cookie management in Node.js (Stop managing cookies in node.js #2550).
• Upgrade cookie package since it now ships ESM (drop the shim).
• Migrate to undici@latest now that node@20 is dropped.
• Remove graphql.* methods. Make GraphQL mocking link-first: graphql.link().
• Delete src/core/utils/handleRequest.ts, it's no longer used by anything.
• Reconsider life-cycle events. Things like GraphQL subscriptions or SMTP cannot have events. Are events even needed?
• Refactor WebSocket events. connection -> websocket:connection. Ensure the WebSocket connection life cycle is sufficiently represented with events.
• Consider lazy interceptors, if feasible.
• Migrate to the new Interceptors architecture (feat: adopt the new interceptors architecture #2767).
• Drop deferred-promise in favor of Promise.withResolvers().
• Remove fallback /node, /native directories.
• Rename all modules to kebab-case.
• Adopt multi-project Vitest setup. Use VBM for most browser tests. Use Playwright only for multi-page/otherwise impossible tests in VBM.
• Drop webpack and its dependencies.
• Add http.connect(), http.query(), and any other methods we can now intercept. They wont do anything in the browser, let them be. Add Node.js tests.

Todos

• Document the changes.
• Write the migration guidelines.
• Stress-test the features.

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commit: 2a80603

[socket-security]

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

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​commitlint/​cli@​21.2.1
	@​msw/​url@​0.1.2
	publint@​0.3.22
	graphql-ws@​6.1.1
	@​types/​serviceworker@​0.0.199
	undici@​7.28.0 ⏵ 8.8.0	-6		+1	-1
	tsdown@​0.22.13
	typescript@​7.0.2
	tough-cookie@​6.0.2
	cookie@​2.0.1
	@​fastify/​websocket@​11.3.0
	oxlint@​1.75.0
	@​mswjs/​interceptors@​0.41.9 ⏵ 0.42.1	+12		+1	-1
	knip@​6.29.0
	@​commitlint/​config-conventional@​21.2.0
	lint-staged@​17.1.1
	graphql-yoga@​5.21.2
	graphql@​16.14.2 ⏵ 17.0.2	+1
	prettier@​3.9.6

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[socket-security]

All alerts resolved. Learn more about Socket for GitHub.

This PR previously contained dependency changes with security issues that have been resolved, removed, or ignored.

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[dsonet]

Hey @kettanaito, thanks a lot for your great work!

Is it possible to include this feature? Here’s the link: #2357
It would be nice if it could cross the finish line.

[kettanaito]

@dsonet GraphQL subscriptions will likely make it either to 3.0 or even to 2.0. They aren't as tedious to implement with the new architecture now. I've introduced the concept of handlers merging in the recent changes to 2.0 and that was the missing piece for the subscriptions.

As always, if your company needs that support in MSW, please consider becoming a sponsor! Thank you.