ts:类型

let isDone:boolean = true

let age:number = 123

let newName:string = "aaa"

let u:undefined = undefined

let n:null = null;

let uDemo:number=null
let uDemo1:number=undefined


let notSure:any = 4
notSure="sss"
notSure=true
notSure=null
notSure.name = "111"

let numOrString:number|string = 111

let arrOfNumber :number[] =[1,2,3]
let arrOfNumber1 :string[] =['a','b']

let usr:[string,number] = ['aaa',111]