i++和++i的问题？

Question

var a = [1,2,3,4];

var i = 1;

console.log(a[i++]);//2

console.log(a[i++]);//3

Answer 1

i++是后加 先返回i值，再给i+1，意思是console.log(a[i++]);//2这句先执行console.log(a[i]);然后再i = i+1;搜一下前加 后加