动态显示文本框的字符串数(ajax入门小程序)
首先添加一个html页其页面代码如下:
<html><head><title>在ASP.NET的第一个Ajax小程序</title><link rel="stylesheet" type="text/css" href="../css/main.css"/>
<script language="javascript">
var xmlHttp function showHint(str)
{
if (str.length > 0) { var url="GetRequest.aspx?name=" + str if (window.ActiveXObject) { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
} xmlHttp.onreadystatechange=stateChanged xmlHttp.open("POST", url , true) xmlHttp.send(null) } else { document.getElementById("txtHint").innerHTML="" } } function stateChanged() { if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") { document.getElementById("txtHint").innerHTML=xmlHttp.responseText } }
</script></head><body><div class=content><h1>纯Ajax实现的小程序</h1><form> <p>输入一个字符串:<input type="text" id="txt1"onkeyup="showHint(this.value)"></p><p> 字符串的长度: <span id="txtHint"></span></p> </form> </div></body></html>述代码中GetRequest.aspx?name=" + str 指明将请求页面GetRequest.aspx并把用户输入的字符串传递给页面GetRequest.aspx,所以下一步就是建立GetRequest.aspx页面计算字符串长度,后台代码如下:
using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;public partial class PureAjax_GetRequest : System.Web.UI.Page{ protected void Page_Load(object sender, EventArgs e) { if (Request.QueryString["name"] != "") Response.Write(Request.QueryString["name"].Length); else Response.Write("NULL"); }}