Deep generate dot notation in TypeScript with example

DeepDotKey.ts

interface Hello {
    foo : World;
    bar: Number;
    array: World[]
}
interface World {
    greeting: string;

}

type DeepDotKey<T> = {
    [P in keyof T]: DeepDotKey<T[P]>;
} & (() => string | number);

function deepDotKey<T>(sep: string = '.', prev?: string | number): DeepDotKey<T> {
    return new Proxy<any>(() => prev, {
        get: (_, next) => {
            if (typeof next === "symbol") {
                throw new Error("Cannot use symbols with deepDotKey.");
            }
            return deepDotKey(sep, prev ? `${prev}${sep}${next}` : next);
        },
    });
}

const _def = deepDotKey<Hello>();

console.log(_def.foo.greeting());
console.log(_def.array[0].greeting());