一些思考

interface Person {
    name: string;
  age: number;
  walk: () => void;
}
interface bird {
    name: string,
  age: number;
  fly: () => void  
}
// 提取出 name 和 age 作为必须属性
// 非共有的fly 和 walk 作为非必须属性
// TODO: 更好的做法，这写法太耦合了
// export type Alien = Omit<Person, 'walk'> &
//   Omit<Bird, 'fly'> &
//   Partial<Pick<Person, 'walk'> & Pick<Bird, 'fly'>>;
 const aliesn: Alien[] = [
       {
             name: '111',
      age: 11,
         },
    {
             name: '222',
      age: 2,
      fly: () => {}
         },
    {
             name: '3333',
      age: 3,
      walk: () => {}
         },
    {
             name: '4444',
      age: 4,
      fly: () => {}
         walk: () => void;
         },
 ]

// type Z = { id: number, age?: number } // 共有属性原样输出
// type Z = { id: number }
type PickerRequiedKeys<T> = {
    [K in keyof T]-?: {} extends Pick<T, K> ? never : K;
}[keyof T]
type PickCommonKeys<A, B> = {
    [K in keyof A & keyof B]: A[K] extends B[K]
      ? B[K] extends A[K]
            ? K
            : never
        : never
}[keyof A & keyof B]
type Z1 = Pick<X, PickCommonKeys<X, Y>>
type Z2 = Pick<X, PickRequiredKeys<Pick<X, PickCommonKeys<X, Y>>>>

interface Person {
  name: string,
  age: number;
  walk: () => void;
}
interface Bird {
  name: string,
  age: number;
  fly: () => void
}
export type Alien = Person | Bird
// 赋值的时候没有问题
const test: Alien = {
  name: 'asd',
  age: 12,
  walk: () => {},
  fly: () => {}
}
// 访问的时候报错
// TS2339: Property 'walk' does not exist on type 'Alien'.
// Property 'walk' does not exist on type 'Bird'.
console.log(test.walk)
// ts 无法判断是 bird 还是 person, 可以用 in 把类型搜索，让 ts 更好推断
console.log('walk' in test ? test.walk() : test.fly())

Promise 和 PromiseLike

// the return type of an async function or method must be the global Promise<T> type. 
//Did you mean to write 'Promise<void>'?(1064)
async function getUserInfo(user: string): PromiseLike<void> {
    return Promise.resolve(undefined);
}
//
async function getUserInfo(user: string): Promise<void> {
    return Promise.resolve(undefined);
}