定义函数
function func (arg1: type, arg2: type): type {//函数体};orconst func = (arg1: type, arg2: type): type =>{//函数体};
定义函数类型
let add = (arg1:number, arg2:number) => numberadd = (arg1:number, arg2:number) : number => arg1 + arg2;//使用接口定义函数类型Interface Add {(x:number, y:number): number}let add :Add =(arg1:number,arg2:number) :number => arg1 + arg2
