Industry standard API mocking for JavaScript.

api api-mocking devtools mock mock-service-worker mocking mocking-framework mocking-library msw mswjs service-worker
6 Open Issues Need Help Last updated: Feb 2, 2026

Open Issues Need Help

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AI Summary: This GitHub issue reports a bug in MSW where unhandled errors thrown within a WebSocket `connection` event listener are not propagated to the client-side `WebSocket.onerror` event. This prevents users from effectively testing error handling scenarios for WebSocket connections mocked by MSW. A reproduction repository and code snippet are provided to demonstrate the issue.

Complexity: 3/5
bug good first issue api:ws

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker
bug good first issue scope:node

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker

AI Summary: This GitHub issue reports an intermittent bug where requests made immediately after calling `stop` on the Mock Service Worker (MSW) service worker do not always pass through properly. Users observe that a second image sometimes fails to load (either pending or improperly served) in Chromium-based browsers and Safari, particularly after multiple page reloads, suggesting a race condition during service worker unregistration.

Complexity: 4/5
bug help wanted scope:browser needs:triage

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker

AI Summary: This task involves enhancing the Mock Service Worker (MSW) library by publicly exposing selected internal utilities and TypeScript types. This will improve the library's extensibility, allowing advanced users to create custom handlers and integrations more easily and safely, without relying on potentially unstable internal imports. The task includes identifying suitable internal functions and types for exposure, deciding on the optimal export structure, updating documentation, and creating a pull request.

Complexity: 4/5
help wanted feature DX

Industry standard API mocking for JavaScript.

TypeScript
#api#api-mocking#devtools#mock#mock-service-worker#mocking#mocking-framework#mocking-library#msw#mswjs#service-worker