Ever built a function that should accept one of several options — but not more, not less?
In 2025, TypeScript makes it cleaner than ever with a pattern called RequireOnlyOne. One small generic gives you:
✅ Precise API contracts
❌ No runtime ambiguity
💥 Compile-time enforcement
🔍 Use cases:
• A weather API: cityId or coordinates
• A React Avatar: initials or photo URL
• An invoice handler: invoiceId or subscriptionId
🧠 Bonus insight: works great with OpenAPI, and easy to adapt into RequireAtLeastOne.
Skip the boilerplate, prevent misuse, and make future refactors effortless.
👏 Like real-world TS tips? Follow for more clean patterns, no fluff.
https://levelup.gitconnected.com/requireonlyone-in-2025-typescript-trick-for-exactly-one-property-8637ca5e6907
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