how to define typescript return type code example

Example 1: get function return type typescript

type return_type = ReturnType<() => string>; // string
// or
function hello_world(): string {
  return "hello world";
}
type return_type = ReturnType<typeof hello_world>; // string

Example 2: typescript annotate return type

function add(x: number, y: number): number {
  return x + y;
}