js实现省份下拉菜单效果

var provinces=['辽宁','北京','上海','吉林','浙江'];

//最新添加的省份放在最前面

var choice=['请选择...']

var zhejiang=['杭州','嘉兴','宁波','绍兴'];

var shanghai=['金山','闸北','普陀','徐汇'];

var jilin=['长春','辽源','吉林','四平'];

var beijing=['海淀','朝阳','东城','西城'];

var liaoning=['沈阳','大连','盘锦','锦州','辽阳','鞍山']

//城市排序由后到前

var citys=new Array;

citys[0]=choice;

citys[1]=zhejiang;

citys[2]=jilin;

citys[3]=shanghai;

citys[4]=beijing;

citys[5]=liaoning;

function add_option(select,option){

 var target=document.getElementById(select);

 for (var i = option.length - 1; i >= 0; i--) {

  var add_option=document.createElement("option");

  add_option.text=option[i];

  target.add(add_option,null);

  target.lastChild.setAttribute("name",option[i]);

 }

}

add_option("province",provinces);

document.getElementById("province").addEventListener("change",function(){

 var selevted_province=document.getElementById("province");

 var selected_city=document.getElementById("city");

 for (var i = selevted_province.length - 1; i >= 0; i--) {

  selected_city.remove(i);

 }

 var selected=selevted_province.selectedIndex;

 if (selected==0) {

  add_option("city",citys[0]);

  document.getElementById("where_submit").setAttribute("disabled","ture");

 }else{

  add_option("city",citys[selected]);

  document.getElementById("where_submit").removeAttribute("disabled");

 }

})