Typed Object.keys and Object.entries
Helpers that keep key types instead of widening to string, for objects you know the shape of.
- TypeScript
- GreenSnippets
- MIT
- Executed with Node.js 22 (type stripping)
function typedKeys<T extends object>(obj: T): (keyof T)[] {
return Object.keys(obj) as (keyof T)[];
}
function typedEntries<T extends object>(obj: T): { [K in keyof T]: [K, T[K]] }[keyof T][] {
return Object.entries(obj) as { [K in keyof T]: [K, T[K]] }[keyof T][];
}Example / expected output
const prices = { apple: 1.2, pear: 2 };
for (const [name, price] of typedEntries(prices)) {
// name: "apple" | "pear", price: number
}How it works
Object.keys returns string[] because objects may have extra properties at runtime. When you know the object is exactly its declared type (for example a constant), these wrappers give you precise keys back. Do not use them on objects from untrusted input.
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