feat!: 3.0

[kettanaito]

• Fixes Support intercepting navigate requests #1594
• Fixes My app hooks in beforeunload with a confirmation message and then MSW stops working #1105

BREAKING CHANGES

• Deprecate support for Node.js v18 and v20 (feat: drop support for Node.js 18, 20 #2729). The minimal supported Node.js version if v22.
• 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 in 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.

Features

• Support TypeScript 5.9.
• Support intercepting page navigations and form submissions (feat: support navigate requests #2721).
• Migrate from path-to-regexp to @msw/url (feat!: migrate to @msw/url #2678).

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

• Support Node.js v26.
• Migrate to pnpm@11.
• Support TypeScript up to 7.0 (investigate if 7.0 can be supported, too).
• 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.
• Refactor WebSocket events. connection -> websocket:connection. Ensure the WebSocket connection life cycle is sufficiently represented with events.

Todos

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

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commit: 05bde09

[socket-security]

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

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​msw/​url@​0.1.2
	tsdown@​0.22.3
	cookie@​2.0.1
	undici@​7.28.0 ⏵ 8.7.0			+1

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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.