ts中any和unknown的区别

• 赋值时的表现

1. 任意类型可以给any赋值，any也可以给任意类型赋值

let p1:any = 40
let p2:any = 'hellow'
// ...

let p:any = 40

let num:number = p
let str:string = p
let obj:object = p

2. 任意类型可以给unknown赋值，但unknown只能给unknown或any赋值，unknown是TS3.0新增的类型

let p1:unknown = 40
let p2:unknown = 'hellow'
// ...

let p:unknown = 40

let x:unknown = p     //ok
let y:any = p         //ok

let num:number = p  // Type 'unknown' is not assignable to type 'number'
let str:string = p  // Type 'unknown' is not assignable to type 'string'

• 安全性方面比较

unkuown是更加安全的any类型，一般要配合类型收载或类型断言才能对其操作，否则在编译阶段就会报错

let p:unkunwn = 40

p.toFixed(2)  //error
p.length  //error