11、类型别名，字面量，交叉类型

11.1、类型别名

// type aliase

// 普通写法

let sum: (x: number, y: number) => number

const result = sun(1, 2)

// 类型别名写法

type PlusType = (x: number, y: number) => number

let sum2: PlusType

const result2 = sun2(1, 2)

 

11.2、字面量

const str: 'name' = 'name'

const number: 1 = 1

type Directions = 'Up' | 'Down' | 'Left' | 'Right'

let toWhere: Directions = 'left'

 

11.3、交叉类型

interface IName {

name: string

}

type IPerson = IName & {age: number}

let person: IPerson = {name: '123', age: 123}