ITMISS
方法一:function RoundShift(arr , count) {
for (var i = 0; i< count; i++) {
arr.unshift(arr.pop())
}
}
var arr = [1,2,3,4,5,6,7];
RoundShift(arr, 3);
console.log(arr)方法二:var arr = [1,2,3,4,5,6,7];
arr = arr.slice(-3).concat(arr.slice(0,-3))
console.log(arr)