1.partial
2readonly
3pick
4record
5泛型索引
定义数组
interface myArrar<number> {
[n:number]
}
6映射
7 in keyof
8T[P]
8
type Props = {
a: number
b: string
c: boolean
}
type prop1 = Props['a' | 'b']
type prop2 = Props[keyof Props]
9declear