Detailed example of jQuery using $.ajax for instant verification

Detailed example of jQuery using $.ajax for instant verification_jquery

WBOY

Release： 2016-05-16 15:26:20

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The example in this article describes how jQuery uses $.ajax for instant verification. Share it with everyone for your reference, the details are as follows:

Here, jQuery and general processing programs are used to instantly verify whether the student number entered by the user is repeated, and a prompt is given when the cursor leaves the input box.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="AddStudent.aspx.cs" Inherits="AddStudent" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
 <title></title>
 <style type="text/css">
  .clsShow
  {
   font-size: 13px;
   border: solid 1px #cc3300;
   padding: 2px;
   display: none;
   margin-bottom: 5px;
   background-color: #ffe0a3;
  }
 </style>
 <script type="text/javascript" src="Scripts/jquery-1.4.2.js"></script>
 <script type="text/javascript">
  $(function () {
   $("#btnSave").click(function () {
    if ($(".clsShow").html().toString() != "")//存在提示信息，则不允许提交表单
     return false;
    else
     return true;
   });
   $("#txtNum").focus(); //输入焦点
   $("#txtNum").keydown(function (event) {
    if (event.which == "13") {//回车键,移动光标到密码框
     $("#txtName").focus();
     $("#txtNum").trigger("blur");
    }
   });
   $("#txtNum").blur(function () {
    //获取学号
    var strTxtName = encodeURI($("#txtNum").val());
    //开始发送数据
    $.ajax
    ({ //请求验证学号是否重复
     url: "Check.ashx", 
     type: "post",
     //传送请求数据
     data: { txtNum: strTxtName },
     success: function (strValue) { //登录成功后返回的数据
      //根据返回值进行状态显示
      if (strValue == "True") {//注意是True,不是true
       $(".clsShow").css("display", "inline");
       $(".clsShow").html("学号已存在，请修改！");
      }
      else {
       $(".clsShow").hide(); //就是把display属性变成none
       $(".clsShow").html("");
      }
     }
    })
   })
  })
 </script>
</head>
<body>
 <form id="form1" runat="server">
 <div>
  学号:<asp:TextBox 
   ID="txtNum" runat="server"></asp:TextBox>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
   ControlToValidate="txtNum" ErrorMessage="不能为空"></asp:RequiredFieldValidator>
  <div class="clsShow"></div>
  <br />
  姓名:<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" 
   ControlToValidate="txtName" ErrorMessage="不能为空"></asp:RequiredFieldValidator>
  <br />
  数学:<asp:TextBox 
   ID="txtMath" runat="server"></asp:TextBox>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" 
   ControlToValidate="txtMath" ErrorMessage="不能为空"></asp:RequiredFieldValidator>
  <asp:RangeValidator ID="RangeValidator1" runat="server" 
   ControlToValidate="txtMath" ErrorMessage="分数在0-100之间" MaximumValue="100" 
   MinimumValue="0" Type="Integer"></asp:RangeValidator>
  <br />
  英语:<asp:TextBox ID="txtEnglish" runat="server"></asp:TextBox>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" 
   ControlToValidate="txtEnglish" ErrorMessage="不能为空"></asp:RequiredFieldValidator>
  <asp:RangeValidator ID="RangeValidator2" runat="server" 
   ControlToValidate="txtEnglish" ErrorMessage="分数在0-100之间" MaximumValue="100" 
   MinimumValue="0" Type="Integer"></asp:RangeValidator>
  <br />
  语文:<asp:TextBox ID="txtChinese" runat="server"></asp:TextBox>
  <asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server" 
   ControlToValidate="txtChinese" ErrorMessage="不能为空"></asp:RequiredFieldValidator>
  <asp:RangeValidator ID="RangeValidator3" runat="server" 
   ControlToValidate="txtChinese" ErrorMessage="分数在0-100之间" MaximumValue="100" 
   MinimumValue="0" Type="Integer"></asp:RangeValidator>
  <br />
  <asp:Button ID="btnSave" runat="server" Text="保存" onclick="btnSave_Click" />
  <asp:Button ID="btnBack" runat="server" Text="返回" CausesValidation="False" 
   onclick="btnBack_Click" />
  <asp:Label ID="lblMsg" runat="server"></asp:Label>
 </div>
 </form>
</body>
</html>

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General handler Check.ashx code:

<%@ WebHandler Language="C#" class="Check" %>
using System;
using System.Web;
public class Check : IHttpHandler {
 public void ProcessRequest (HttpContext context) {
  context.Response.ContentType = "text/plain";
  string num = context.Request["txtNum"].ToString();
  bool result = false;
  if(num=="12")//为了简化代码，没有访问数据库。实际项目应查询数据库。
  {
   result = true;
  }
  context.Response.Write(result);
 }
 public bool IsReusable {
  get {
   return false;
  }
 }
}

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