type类型转换

开发中经常使用的类型转换

交叉类型及联合类型

interface Bird {
  name: string,
  fly(): void
}
interface Person {
  age: number,
  talk(): void; 
}
type BirdMan = Bird & Person;
let chaoren: BirdMan = {
  name: 'lee', 
  fly() {}, 
  age: 1, 
  talk(){}
}

对象转类型【typeof】

let people = {
  name: "北鸟南游",
  age: 18
}
// 将people对象直接转化为type类型People
type People = typeof people;

限制类型属性【keyof】

type Animal = {
  kinds:string;
  name: string;
  legs: number;
}
// 获取type类型别名的key值
type AnimalKey = keyof Animal; // 'kinds'|'name'|'legs'

映射类型【keyof+in】

type Person = {
  name: string,
  age: number,
  gender: boolean
}
//PersonMap是从Person映射的类型，该类型各属性都变为可选
type PersonMap = {
  [key in keyof Person]?: Person[key]
}
let p1:PersonMap = {name: '北鸟南游'};

内置类型

Partial
Required
Readonly
Pick

内置条件类型

Exclude
Extract
NonNullable
ReturnType
InstanceType