alan
alan
var a = [1,2,3] var b = JSON.parse(JSON.stringify(a)) 完事
数组去重或者判断有没有重复元素用new Set()就ok了.

> ```js > var arr = [1,[2,3,[4,5]],8] > function flatten(arr) { > return arr.toString().split(",") > } > flatten(arr) > ["1", "2", "3", "4", "5", "8"] > ``` > > 这样呢?...
'123'.search(x)
'红蓝蓝黄红黄蓝红红黄红'.split('').sort((a,b) => {if(a=='黄' || b=='蓝'){return -1}}).join('')


> > > undefined 10 20 > > > 代码执行过程: > > > `var a; // undefined` > > > `a = 10; ` > > > `(function () {`...
