js冒泡排序

<script type="text/javascript">
            function sort (arr) {
                for (var i = 0;i<arr.length;i++) {
                    for (var j = 0; j < arr.length-i-1; j++) {
                        if (arr[j]<arr[j+1]) {
                            var temp=arr[j];
                            arr[j]=arr[j+1];
                            arr[j+1]=temp;
                        }
                    }
                }
                return arr;
            }
            var arr=[2,5,3,1,7,8,78,89];
            sort(arr);
            alert(sort(arr));
</script>