'Sys.WebForms.PageRequestManager'为null或不是对象

Question

嗨,我有一个aspx页面,其中我有以下代码

  <asp:ScriptManager ID="scriptManager" runat="server" AsyncPostBackTimeout="500" EnablePageMethods="true">
            </asp:ScriptManager>

            <script type="text/javascript">
          Sys.Application.add_init(BeginRequestHandler);
          Sys.Application.add_init(EndRequestHandler);

          Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);
          Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
          function BeginRequestHandler(sender, args) {
              AsynProcessing('block', 'AlertDiv', 'ProcessingImage');
          }
          function EndRequestHandler(sender, args) {
              AsynProcessing('none', 'AlertDiv', '');
          }
          function AsynProcessing(visstring, elem, img) {
              var adiv = $get(elem);
              adiv.style.display = visstring;
              adiv.image = img;
          }

但是该页面抛出了一个javascrip错误,因为'Sys.WebForms.PageRequestManager'为null或不是对象.我在scriptmanager标签下面放了.我甚至还说道

<xhtmlConformance  mode="Transitional"/>

在web.config.But部分仍然得到相同的错误.
任何帮助深表感谢.提前致谢

Answer 1

使用此代码包装处理程序,以便在调用之前等待加载所有nessesary脚本 Sys.WebForms.PageRequestManager

Sys.Application.add_init(function(){ ... your code ....}

http://msdn.microsoft.com/en-us/library/bb397532.aspx

编辑:这行错误的原因Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandl??er)是还没有加载脚本,所以如果你想处理异步回发,你必须写这样的东西:

Sys.Application.add_init(function(){ 
    Sys.WebForms
       .PageRequestManager
       .getInstance()
       .add_beginRequest(BeginRequestHandler)
});

简单的英语是什么意思？等到所有脚本都已加载(包括Sys.WebForms命名空间)并订阅事件 beginRequest 脚本块应如下所示:

<script type="text/javascript">
    Sys.Application.add_init(function () {
        Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequestHandler);
    });
    Sys.Application.add_init(function () {
        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
    });

    function BeginRequestHandler(sender, args) {
        AsynProcessing('block', 'AlertDiv', 'ProcessingImage');
    }
    function EndRequestHandler(sender, args) {
        AsynProcessing('none', 'AlertDiv', '');
    }
    function AsynProcessing(visstring, elem, img) {
         var adiv = $get(elem);
         adiv.style.display = visstring;
        adiv.image = img;
    }  
</script>