An example tutorial on how to implement three-level linkage between provinces, cities and counties using jQuery

 1 <style type="text/css"> 2     *{margin:0;padding:0;} 3     .selectAll 4       
 { width:400px; 5          margin:100px auto; 6       } 7 </style> 8  9 <div class="selectAll">10     <!--省份-->11     
 <select class="province">12         <option>请选择</option>13     </select>14     <!--城市-->15     <select class="city">16         <option>请选择</option>17     </select>18     <!--地区-->19     <select class="district">20         <option>请选择</option>21     </select>22 </div>

 1 <script src=&#39;./js/jquery.min.js&#39;></script> 2 <script type="text/javascript"> 3 $(function(){ 4 
 //    
 JSON文件放的位置，根据你放的位置更改 5     var url = './js/district.json'; 6 
 //    
 JSON数据为数组，将返回的值赋值给areaData，一次性请求完成 7     var areaData = null; 8 
 //    获取到的数据用模板存放到templateOption，进行DOM重绘 9     var templateOption = "";10 
 //11     var province = $('.province');12     var city = $('.city');13     
 var district = $('.district');14 //    获取JSON格式15     $.getJSON(url,function (data) {16         areaData = data;17         provinceFun();18     })19 
 //    省份20     
 var provinceFun = function(){21         $.each(areaData,function(index,value){22             templateOption += "<option value=&#39;"+value.p+"&#39;>"+value.p+"</option>";23         })24         
 province.html(templateOption);25         cityFun();26     };27 //    城市28     var cityFun = function(){29         templateOption = "";30 
 //        获取省份选取的索引，用get(0)是因为获取$('.province')的第一个，即使$('.province')只有一个。下面也一样。31         var p = province.get(0).selectedIndex;32 
 //        根据JSON格式，获取选取省份对应的市的数组33         $.each(areaData[p].c,function(index,value){34             templateOption += "<option value=&#39;"+value.ct+"&#39;>"+value.ct+"</option>";35         })36 
 //        对城市的option选项进行重绘37         city.html(templateOption);38 //        城市选择好了，触发区县39         districtFun();40     };41 //    区县42     var districtFun = function(){43         templateOption = "";44         var p = province.get(0).selectedIndex;45         var c = city.get(0).selectedIndex;46 
 //        若区县没有，不显示出来47         if(areaData[p].c[c].d == undefined){48             
 district.css('display','none');49         }else{50             
 district.css('display','inline');51             
 $.each(areaData[p].c[c].d,function(index,value){52                 
 templateOption += "<option value=&#39;"+value.dt+"&#39;>"+value.dt+"</option>";53             })
              
 district.html(templateOption);55         }56 57     };58 
 //    点击省份，触动市的变化59     province.change(function(){60         
 cityFun();61     });62 //    点击市，触动地区的变化63     
 city.change(function(){64         districtFun();65     })
 })
 
 </script>