Js 清空select 动态添加select的代码

<script language="javascript">
//先清空select的值，然后添加select的option选项
var allPlan=areaInfo.handlePlan;
var planSelect = document.getElementById("handlePlanID");
 for(var i=planSelect.length-1;i>=0;i--){
  if ((navigator.userAgent.indexOf('MSIE') >= 0) && (navigator.userAgent.indexOf('Opera') < 0)){
   planSelect.remove(i);
  }else if (navigator.userAgent.indexOf('Firefox') >= 0){
   document.getElementById("handlePlanID").remove(i);
  }else{
   document.getElementById("handlePlanID").remove(i);
  }
  }
 
 if(allPlan==""){ //by www.jb200.com
      planSelect.options.add(new Option("无方案", ""));
 } else{
    var allPlanArray=allPlan.split("&&");
    for(var i=0;i<allPlanArray.length;i++){
       var  id=allPlanArray[i].split("##")[0];
       var  name=allPlanArray[i].split("##")[1];
          planSelect.options.add(new Option(name, id));
         if(id==areaInfo.handlePlanID){
          planSelect.options[i].selected=true;
         }
    }
 }
</script>