js 联动

function clearSelect(ctlSelect){
	ctlSelect.options.length = 0;
}
function addOption(select,text,value) {
	if(text != "")	{
	   var obj   = document.createElement("option");
obj.text  = text;
	   obj.value = value;
	   select.options.add(obj);
	}
}	
function add_city(){    
		var countryId = document.form1.selectcountry.value;
		clearSelect(document.form1.selectcity);
		addOption(document.form1.selectcity,'全部','');		
		if(countryId != ""){
			for(var i = 0; i < CityList.length; i++)  {			
				if( CityList[i].id1 == countryId) 
				    addOption(document.form1.selectcity,CityList[i].name1,CityList[i].id2);								
				}
			  }
	if(document.form1.selectcity.options[0]!=null) document.form1.selectcity.options[0].selected = true;
}