3.1.1、 箭头函数
function go(){console.log("hello world")}go();var go = function(){console.log("hello world")}
如果箭头函数中只有一段语句可以简写
var show = ()=>{console.log("world")}var text = ()=>console.log("text");text();
3.1.2、箭头函数的参数
var go = x =>console.log(x);var sum = (x,y)=>{console.log(x+y)};go(10);sum(3,4);
