Get Promised return type of an async function in TypeScript

promised_returned_type.ts

type PromisedReturnType<T extends (...args: any) => any> = T extends (...args: any[]) => PromiseLike<infer R> ? R : any

//usage
async function f1() {
  return "Value";
}

async function f2(): Promise<number> {
  return Promise.resolve(5);
}

type returnTypeoff1 = PromisedReturnType<typeof f1>; //string
type returnTypeoff2 = PromisedReturnType<typeof f2>; //number

TS 4.5 announces Awaited keyword which does the same thing but better please use that now