Retrieve return type of function w/o calling the function

问题

Say I have a function like this in TypeScript:

export const foo = function(){

   return {
     a: 1,
     b: true,
     c: 'bar'
   }

};

if I import this function into another file:

import {foo} from './foobar';

My question is - is there a way to get the return type of foo without actually calling foo?

回答1:

This is now possible with Typescript 2.8

let foo = function() {
   return {
     a: 1,
     b: true,
     c: 'bar'
   }
};

type ComplexObj = ReturnType<typeof foo>;  // {a: number, b: boolean, c: string}

来源：https://stackoverflow.com/questions/50263415/retrieve-return-type-of-function-w-o-calling-the-function