ASP.Net WebForm JQuery 呼叫 CodeBehind方法 (手動postback)

JQuery

$('#myTextBoxB').keypress(function (e) {
    if (event.which == 13) {

        blockUI();
        var param = '{ ' +
            '"Event":"keypress", ' +
            '"A":"' + $("#myTextBoxA").val() + '", ' +
            '"B":"' + $("#myTextBoxB").val() + '"' +
            ' }';
            
        //第1個參數 eventTarget, 第2個參數 eventArgument
        __doPostBack("<%=this.myTextBoxB.ClientID%>", param);
    }
});

Code Behind

protected void Page_Load(object sender, EventArgs e)
{

  if (!IsPostBack)
  {
  
  }
  else
  {
     string eventTarget = Request.Params.Get("__EVENTTARGET");
     string eventArgument = Request.Params.Get("__EVENTARGUMENT");
  
     ParamData PData = Newtonsoft.Json.JsonConvert.DeserializeObject<ParamData>(p_EventArgument);

     if (PData.Event == "keypress") 
     {
       //處理還輯
     }
  }

}

public Class ParamData
{
  public string Event {get; set;}
  public string A {get; set;}
  public string B {get; set;}
}