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jQuery+JSON realizes AJAX secondary linkage example analysis_jquery

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2016-05-16 15:24:451286browse

The example in this article describes the method of jQuery+JSON to achieve AJAX secondary linkage. Share it with everyone for your reference, the details are as follows:

BackendHandler.ashx

<%@ WebHandler Language="C#" Class="Handler" %>
using System;
using System.Web;
using System.Data;
public class Handler : IHttpHandler
{
 Common coObj = new Common();
 public void ProcessRequest(HttpContext context)
 {
  if (context.Request.Params["n"] != null)
  {
   string num = context.Request.Params["n"].ToString();
   context.Response.ContentType = "text/plain";
   string str = "select * from address where a_num2=" + num;
   DataTable dt = coObj.GetTable(str);
   string json = JSONHelper.DataTableToJSON(dt);
   context.Response.Write(json);
  }
 }
 public bool IsReusable
 {
  get
  {
   return false;
  }
 }
}

Front-end dropdownlist.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>dropdownlit </title>
<meta name="Generator" content="EditPlus" />
<script type="text/javascript" src="js/jquery-1.5.2.js"></script>
<script type="text/javascript">
 $(function(){
   InitData(0);
 });
 function InitData(n)
 {
   $.ajax({
   type:"POST",
   dataType:"json",
   url: "Handler.ashx",
   data:{"n":n},
   success:function(json){
    $.each(json,function(i,n){
     var pro=$("#dl1");
     $(""+ n.A_Name +"").appendTo(pro);
    });
   }
  });
 }
 function GetCity(n)
 {
  var city=$("#dl2");
  city.html("");
   $.ajax({
   type:"POST",
   dataType:"json",
    url: "Handler.ashx",
   data:{"n":n},
   success:function(json){
    $.each(json,function(i,n){
     $(""+ n.A_Num1 +">"+ n.A_Name +"").appendTo(city);
    });
   }
  });
 }
</script>
</head>
<body>
 <select id="dl1" onchange="GetCity(this.value)">
 </select>
 <select id="dl2">
 </select>
</body>
</html>

I hope this article will be helpful to everyone in jQuery programming.

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