js联动菜单 JavaScript实现三级联动菜单效果

时间:2021-03-29 geewonii 人气:0

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三级联动考察的应该是对于数据的处理，只要清楚其中的关系，再多几级都是一样的：

html部分：

<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8" />
 <title>3级联动菜单</title>
 <script>
 var region = {
  广东:
  {
  "广州":["广州1","广州2","广州3"],

  "珠海":["珠海1","珠海2","珠海3"],

  "佛山":["佛山1"]
  },
  湖南:
  {
  "常德":["石门","桃源","临澧","汉寿"],

  "益阳":["益阳1","益阳2","益阳3"]
  }
 }
 </script>
</head>
 <body>

 <select id="province" onchange="change(this.value);">
  <option>请选择省份</option>
 </select>

 <select id="city" onchange="countyChange(this.value);">
  <option>请选择地市</option>
 </select>

 <select id="county">
  <option>请选择县城</option>
 </select>
 <script src='test.js'></script>
 </body>
</html>

js部分：

var province = document.querySelector("#province");
 var city = document.querySelector("#city");
 var county = document.querySelector("#county");
 //二级联动不用定义你选的省份,直接用省份(key)来决定下面的市(value)值
 var provinceName = null;

 for (ele in region){
 var op = new Option(ele , ele , false , false); //new Option("文本","值",true,true).后面两个true分别表示默认被选中和有效
 //console.log(op);
 province.options[province.length] = op;
 }

 var change = function(src){
 city.innerHTML = "";
 if(src === '请选择省份'){
  var op = new Option('请选择地市' , '请选择地市' , false , false);
  city.options[0] = op;
 }else{
  for (index in region[src]){
  //console.log(index);
  var op = new Option(index , index , false , false);
  city.options[city.length] = op;
  }
 }
 //记住选择省份的值
 provinceName=src;
 countyChange(city.value)
 }

 var countyChange = function(src2){
 county.innerHTML = "";
 if(src2 === '请选择地市'){
  var op = new Option('请选择县城','请选择县城', false , false);
  county.options[0] = op;
 }else{
  for (index in region[provinceName][src2]){
  //console.log(index);
  var op = new Option(region[provinceName][src2][index] , region[provinceName][src2][index] , false , false);
  county.options[county.length] = op;
  }
 }
 }

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