JavaScript函数式编程
Arrary.slice 是纯函数,固定的输入有固定的输出 ```javascript var arr=[1,2,3]; arr.slice(0,2); < [1,2] arr.slice(0,2); < [1,2] ``` Array.splice 是不纯的函数,有副作用 ``` arr.splice(0,2) < [1,2] arr.splice(0,2) < [3] arr.splice(0,2) < [] ``` ``` //es6 var checkage = age => age > 18; ``` [1](https:/...