JavaScript反转数组

var arr=[1,2,11,4,5,6,7,8,9];
    //遍历循环次数为数组一半，将首尾元素通过第三方置换
    for (var i = 0; i < arr.length/2;i++){
        var temp = arr[i];
        arr[i] = arr[arr.length-1-i];
        arr[arr.length-1-i] = temp;
    }
    console.log(arr);