TypeScript中类型别名

// 类型别名
let sum: (x: number, y: number) => number
const result = sum(1, 2)

type PlusType = (x: number, y: number) => number
let sum2: PlusType
const result2 = sum2(2, 3)

// 联合类型
type StrOrNum = string | number
let result3: StrOrNum = '123'
result3 = 123
let union = 1  | 2 | 3 | 4
// 字面量
const str: 'name' = 'name'
const number: 1 = 1


type Directions = 'Up' | 'Down' | 'Left' | 'Right'
let toWhere: Directions = 'Right'
// 交叉类型
interface IName {
  name: string
}
type IPerson = IName & {age: number}
let person: IPerson = { name: 'my name', age: 123 }