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formsVercel

Unsaved Changes

MUST

MUST: Warn on unsaved changes before navigation

Warn before navigation when data could be lost

Bad

Good

Why it matters

Track form modifications and show a confirmation dialog if the user tries to navigate away or close the tab with unsaved changes. Use the beforeunload event for page unload and custom logic for in-app navigation.

References

Built by Gleb Stroganov, design engineer at Evil Martians.

The rules come from other people's skills and guidelines — Vercel, Rauno Freiberg, @Ibelick, impeccable, Emil Kowalski, Tailwind, RAMS — each one credited on the Sources page. The work here is extraction and wiring: every rule is pulled into one corpus, given a good and a bad example you can operate, a MUST/SHOULD/NEVER rule an agent can paste, and a link back to where it came from.