[TOC] ~~~ //es5 function add(x,y){ var sum = x+y; console.log(sum); } ~~~ ## 1.箭头函数 ~~~ //es6 const add=(x,y)=>{ let sum = x+y; console.log(sum); } ~~~ #### 1.2省略return ~~~ const add=(x,y)=>{ return x+y; } ~~~ ~~~ //简写 const add=(x,y)=>x+y; console.log(add(1,2)); ~~~ ## 2.函数参数 #### 2.1参数展开 >Tip: ...args必须是最后一个参数 - 收集参数 ~~~ function show(a,b,...args){ console.log(a); console.log(b); console.log(args); //2,3,4,5 } show(1,2,3,4,5) ~~~ - 展开数组 ~~~ let arr = [1,2,3]; function test(a,b,c){ alert(a); alert(b); alert(c); } test(...arr); ~~~ #### 2.2默认参数 ~~~ function test(a=10,b){ console.log(a+b); } test(20,10) ~~~