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How our "perfect" one-line isOwner() function in Next.js started always returning true. Spoiler: It is because of server functions... Wrote about the bug, the fix, and the "magic" that caused it: marma.dev/articles/202... #webdev #javascript #typescript #react #nextjs #serverfunctions

marma.devmarma.dev

Pushkar S

@semaphores.dev

Might be a noob question, but could this potentially have been avoided by using TS and annotating the return type of isOwner as boolean?

2/11/25, 11:41 am0 reposts1 like

MRK

@marma.dev

2 Nov 2025

We are using TypeScript. We could also explicitly set the return type, but the problem is that the types don't exist during runtime. They are being checked through the LSP during development and before building. Our function was being changed to an async one after type checking.