HTML option排序功能

function sortRule(a,b) {    var x = a._text;    var y = b._text;    return x.localeCompare(y);}function op(){    var _value;    var _text;    var _selected;}function sortOption(selectObj){    var obj = document.getElementById(selectObj);    var tmp = new Array();    for(var i=0;i<obj.options.length;i++){        var ops = new op();        ops._value = obj.options[i].value;        ops._text = obj.options[i].text;        ops._selected = obj.options[i].selected;        tmp.push(ops);    }    tmp.sort(sortRule);    for(var j=0;j<tmp.length;j++){        obj.options[j].value = tmp[j]._value;        obj.options[j].text = tmp[j]._text;        obj.options[j].selected = tmp[j]._selected;    }}