1-3 函数

1.错误

function go(a:number,b:number){
    return a+b
}
go(1,"12");

2.正确

function go(a:number,b:number):number{    //:number 函数返回值是number
    return a+b
}
go(1,12);

函数

/* 没有返回值 */
function go():void{  ----void:没有指定数据类型
    console.log("go");
}
/* 有返回值 */
function show(val:string):string{
    return val
}

1.默认参数

var str = "hello world";
function http(method='get'){  //method 
    console.log(method);
}
http(); 
http('post')  //method='post'

function http(method:string='get'):void{
    console.log(method);
}
http();
http('post')

2.可选参数

function getInfo(name:string,age?:number):void{
  console.log(name+age);
}
getInfo('Nihao')