智能社- 牛逼的splice

1.

    <script>
        /*splice(start,len)从那个位置开始删除几项*/
            var arr = [1,2,3,4,5,6];
            var removed = arr.splice(2,3);
            alert(arr);//[1,2,6] // 从下标为2的位置往后删除3个
            alert(removed)//[3,4,5]

        /*splice(start,len,...)  当len 为 0 的时候为插入*/
            var arr2 = [1,2,3,4,5];
            var removed  = arr2.splice(2,0,"a","b","c"); //从下标为2的位置删除0个，然后插入"a","b","c"
            var removed  = arr2.splice(2,0,["a","b","c"]); //从下标为2的位置删除0个，然后插入["a","b","c"]
            alert(arr2); // [1,2,"a","b","c",3,4,5]
            alert(removed == undefined);//空

        /*splice(start,len,...) ，当len不为0的时候*/
            var arr3 = ["hello","world","js","java"];
            var removed = arr3.splice(1,2,[1,2,3,4,5,6]);//先从下标为1的位置往后删除2个元素，然后添加数组进来
            alert(arr3);//["hello","java",1,2,3,4,5,6]
            alert(removed );//["world","js"]
    </script>