Type Indexing

Type indexing refers to the ability to define types that can be indexed by a key that is not known in advance, using an index signature to specify the type for properties that are not explicitly declared.

type Dictionary<T> = {
    [key: string]: T;
};
const myDict: Dictionary<string> = { a: 'a', b: 'b' };
console.log(myDict['a']); // Returns a