javascript select options sorting (maintaining the integrity of the option object)_form effects

<select id="select1" size="6"> <option> </option>111<option> </option>333<option> </option>444<option> </option>222<option> </option>333</select> <input type="button" value="sort" onclick="sort();">
[Ctrl A select all Note: If you need to introduce external Js, you need to refresh to execute

]<script> function addOption(object, object2) { each(object2, function(o, index) { object.options[index] = o; }) } function sortlist(sortName,isDesc) { var what = document.getElementById(sortName); this._options = map(what.options, function(o) { return o; }); this._options.sort( function(a, b) { if (a.text > b.text) { return isDesc == true ? 1 : -1; } else { return isDesc == true ? -1 : 1; } }); what.options.length = 0;// clear current options addOption(what, this._options); } function map(object, callback, thisp) { var ret = []; each.call(thisp, object, function() { ret.push(callback.apply(thisp, arguments)); }); return ret; } function each(object, callback) { if (undefined === object.length) { for ( var name in object) { if (false === callback(object[name], name, object)) break; } } else { for ( var i = 0, len = object.length; i < len; i++) { if (i in object) { if (false === callback(object[i], i, object)) break; } } } } var sOrder = true; function sort(){ if(sOrder){ sOrder = false; }else{ sOrder = true; } sortlist("select1",sOrder); } </script>