asp.net 在TextBox里面创建一个默认提示，例如：搜索。

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 1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Recipe1.aspx.cs" Inherits="Recipe1" %>
 2  
 3  <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 4  <html xmlns="http://www.w3.org/1999/xhtml">
 5  <head runat="server">
 6      <title>Recipe1</title>
 7      <script src="Scripts/jquery-1.4.1-vsdoc.js" type="text/javascript"></script>
 8      <style type="text/css">
 9          .defaultText
10  {
11              font-style: italic;
12              color: #CCCCCC;
13  }
14  </style>
15      <script type="text/javascript">
16          $(document).ready(function () {
17  var searchBox = $("#<%=txtSearch.ClientID %>"); // 通过ClientID获取服务器控件ID
18              searchBox.focus(function () {
19  if (searchBox.val() == this.title) { // TextBox控件ToolTip属性转换为Html为title属性
20                      searchBox.val("");
21                      searchBox.removeClass("defaultText");
22                  }
23              });
24              searchBox.blur(function () {
25  if (searchBox.val() == "") {
26                      searchBox.val(this.title);
27                      searchBox.addClass("defaultText");
28                  }
29              });
30              searchBox.blur();
31          });
32  </script>
33  </head>
34  <body>
35      <form id="form1" runat="server">
36      <p>
37      </p>
38      <div align="center">
39          <fieldset style=" 400px; height: 80px;">
40              <p>
41                  <asp:TextBox ID="txtSearch" runat="server" Width="200px" CssClass="defaultText" ToolTip="请输入搜索的关键字"></asp:TextBox>
42                  <asp:Button ID="btnSearch" runat="server" Text="搜索" /></p>
43          </fieldset>
44      </div>
45      </form>
46  </body>
47  </html>