数组过滤
用了这么久的JavaScript，现在才慢慢摸索更简单的方法
array.filter()，这个方法用处还是挺多的，比如遍历数组中的数组
下面我们结合es6的箭头函数，来看看
var arr1 = [
{key:1,value:12},
{key:2,value:15},
{key:3,value:"mio"}
]
var arr2 = [
{
key:1,
value:[1,2,3]
},
{
key:2,
value:[{key:12,value:"akuma"},{key:13,value:"mio"},{key:14,value:"CVdongdong"}]
}
];
var str1 = 1,str2 = 2;
var res1,res2;
res1 = arr1.filter(k=>k.key == str1)[0].value
res2 = arr2.filter(k=>k.key == str2)[0].value.filter(k=>k.key == 13)[0].value; //这一行就这么简单
console.log(res2)就写这么多了