....

function getSortArray(lst) {
    var lstBeforeSort = [];
    for (var i in lst) {
        lstBeforeSort.push(lst[i]);
    }
    var lstAfterSort = lst.sort(function (a, b) {
        return b - a
    });
    var sortArray = [];

    function isContains(arrayList, o) {
        for (var i in arrayList) {
            if (arrayList[i] == o)
                return true;
        }
        return false;
    }

    for (var i in lstAfterSort) {
        for (var a in lstBeforeSort) {
            if (lstAfterSort[i] == lstBeforeSort[a]) {
                //如果在排序数列里面已经有了这个索引  那么继续往下找
                if (isContains(sortArray,a))
                    continue;
                else {
                    sortArray.push(a);
                    break;
                }
            }
        }
    }
    return sortArray;
}