ASP.NET AJAX Sys未定义的解决方法

在Web.Config的system.web里面添加以下代码

<httpHandlers>
　 <remove verb="*" path="*.asmx"/>
<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory,System.Web.Extensions,Version=1.0.61025.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"/>
<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory,System.Web.Extensions,Version=1.0.61025.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35"/>
<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler,System.Web.Extensions,Version=1.0.61025.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35" validate="false"/>
</httpHandlers >