objectKeys

Like Object.keys() but with a better return type

Functionally identical to Object.keys() except that the return type ain't just string but a typed array.

import { assert, type Equals } from "tsafe/assert";
import { objectKeys } from "tsafe/objectKeys";

const obj = {
	a: 1,
	b: "ok",
	c: null,
};

//    v keys is an array of "a", "b", "c"
const keys = objectKeys({
	a: 1,
	b: 2,
	c: 3,
});

assert<Equals<typeof keys, ("a" | "b" | "c")[]>>();

WARNING: Only use with object you have instantiated yourself. Some keys that are not in the type might be present on the object at runtime!

const o = { p: 33, k: "ok", r: false };
const x = objectKeys<{ p: number; k: string }>(o);
//x is of type ("p" | "k")[] but actually x === ["p", "k", "r"]