向左移动n位的代码

var n = 2;
var arr = [1,2,3,4,5,6];
var arr1 = arr.slice(0,n);
var arr2 = arr.slice(n,6)

arr1 = arr1.reverse();
arr2 = arr2.reverse();

var arr3 = arr1.concat(arr2).reverse();

console.log(arr3); // [3,4,5,6,1,2] 字符串左移两位