敢问大神们js中alert(["a","b","c","d","e"][[1,2],3,4]);是什么意识啊啊

Question

敢问大神们js 中 alert(["a","b","c","d","e"][[1,2],3,4]);是什么意识啊啊

Answer 1

["a","b","c","d","e"] 表示一个数组
在数组后面的中括号表示 数组的下标
中括号间的 [1,2],3,4会按表达式来处理,[1,2],3,4是一个逗号表达式,取最后一个 4
这个相当于
var a = ["a","b","c","d","e"];
alert(a[4]);