function attr(name:string):string;
function attr(age:number):string;
function attr(nameorage:any):any{
if(nameorage &&typeof nameorage ==="string"){//代表当前是名字
alert("ming")
}else{
alert("age");
}
}
attr("hell");
attr(10);
原文：https://www.cnblogs.com/allyh/p/10692802.html