Index Signatures

In TypeScript, we can use string, number, and symbol as index signatures:

type K = {
    [name: string | number]: string;
};
const k: K = { x: 'x', 1: 'b' };
console.log(k['x']);
console.log(k[1]);
console.log(k['1']); // Same result as k[1]

Please note that JavaScript automatically converts an index with number to an index with string, so k[1] or k["1"] returns the same value.