jquery – PageMethod返回整个页面

$.ajax({
type: "POST",url: "ajaxPage.aspx/testMethod",data: "{test:'test'}",contentType: "application/json; charset=utf-8",dataType: "json",success: function (result) {
    $("#span_result").html(result.d).fadeIn();
},error: function (msg) {
     $("#span_result").hide();
}
}); 

//ajaxPage.aspx.cs
[System.Web.services.WebMethod]
public static String testMethod(String test)
{
     return test;
}