let a :{name:string,[xx:string]:any}
a = {name:'小明',age:28,gender:'男'}            正确
a = {name:111,age:28,gender:'男'}               错误，name必须是字符串
//这句话的意思就是a对象中  name是必填的并且只能是字符串，后面属性名是字符串，不必填，假如加的话值可以为任意类型
//  后面的任意类型设置为string，name中的number会失效，也会跟着把校验改为string
let b = {name:number,[xx:string]:string}b = {name:222,age:28,gender:'男'}            错误，name必须是字符串,age必须为字符串
b = {name:111,age:28,gender:222}               错误，name必须是数字串并且每一项必须为字符串