JavaScript实现下拉列表框数据增加、删除、上下排序的方法

<title>下拉列表数据上下排序</title><SCRIPT LANGUAGE="JavaScript"><!-- Beginfunction move(fbox,tbox) {var i = 0;if(fbox.value != "") {var no = new Option();no.value = fbox.value;no.text = fbox.value;tbox.options[tbox.options.length] = no;fbox.value = "";  }}function remove(box) {for(var i=0; i<box.options.length; i++) {if(box.options[i].selected && box.options[i] != "") {box.options[i].value = "";box.options[i].text = "";  }}BumpUp(box);} function BumpUp(abox) {for(var i = 0; i < abox.options.length; i++) {if(abox.options[i].value == "") {for(var j = i; j < abox.options.length - 1; j++) {abox.options[j].value = abox.options[j + 1].value;abox.options[j].text = abox.options[j + 1].text;}var ln = i;break;  }}if(ln < abox.options.length) {abox.options.length -= 1;BumpUp(abox);  }}function Moveup(dbox) {for(var i = 0; i < dbox.options.length; i++) {if (dbox.options[i].selected && dbox.options[i] != "" && dbox.options[i] != dbox.options[0]) {var tmpval = dbox.options[i].value;var tmpval2 = dbox.options[i].text;dbox.options[i].value = dbox.options[i - 1].value;dbox.options[i].text = dbox.options[i - 1].textdbox.options[i-1].value = tmpval;dbox.options[i-1].text = tmpval2;   }  }}function Movedown(ebox) {for(var i = 0; i < ebox.options.length; i++) {if (ebox.options[i].selected && ebox.options[i] != "" && ebox.options[i+1] != ebox.options[ebox.options.length]) {var tmpval = ebox.options[i].value;var tmpval2 = ebox.options[i].text;ebox.options[i].value = ebox.options[i+1].value;ebox.options[i].text = ebox.options[i+1].textebox.options[i+1].value = tmpval;ebox.options[i+1].text = tmpval2;   }  }}// End --></script><form ACTION="" METHOD="POST"><table><tr><td><input type="button" value="增加" onclick="move(this.form.list1,this.form.list2)" name="B1"><br><input type="button" value="删除" onclick="remove(this.form.list2)" name="B2"><br><input type="button" value="向上" onclick="Moveup(this.form.list2)" name="B3"><br><input type="button" value="向下" onclick="Movedown(this.form.list2)" name="B4"></td><td><select multiple size=7 name="list2"><option value="one">ASP</option><option value="two">PHP</option><option value="three">ASP.NET</option><option value="four">JAVA</option><option value="five">DELPHI</option></select></td></tr><tr><td><input type="text" name="list1" value=""></td></tr></table></form>