typescript get the promise return type

1new Promise<boolean>((res, rej) => {
2  res(true);
3})
4.then(res => {
5  console.log(res);
6  return false;
7})
8  .then(res => {
9  console.log(res);
10  return true;
11})
12  .then(res => {
13  console.log(res);
14})
15  .catch(error => {
16  console.log('ERROR:', error.message);
17});

1type AsyncReturnType<T extends (...args: any) => any> =
2	T extends (...args: any) => Promise<infer U> ? U :
3	T extends (...args: any) => infer U ? U :
4	any

1function promiseOne() {
2  return Promise.resolve(1)
3}
4    
5const promisedOne = promiseOne()
6    
7// note PromiseLike instead of Promise, this lets it work on any thenable
8type ThenArg<T> = T extends PromiseLike<infer U> ? U : T
9    
10type PromiseOneThenArg = ThenArg<typeof promisedOne> // => number
11// or
12type PromiseOneThenArg2 = ThenArg<ReturnType<typeof promiseOne>> // => number
13