js数组排序

/**
 * 数组排序
 * list为数组 parm为排序字段 b为排序方向
 */
var _sort = function (list, parm, b) {
    var down = function (x, y) {
        return (eval("x." + parm) > eval("y." + parm)) ? -1 : 1;
    }
    var up = function (x, y) {
        return (eval("x." + parm) < eval("y." + parm)) ? -1 : 1;
    }
    if (b == "down") {
        list.sort(down);
    }
    else {
        list.sort(up);
    }
    return list;
}