點選按鈕送出後使按鈕變灰不可用

.aspx <script language="javascript"> function   abc() { var   mybutton=document.getElementById("Submit1"); mybutton.disabled=true;         //變灰 __doPostBack("Submit1","");     //執行伺服器端Submit1的click事件 }   </script> <form id="Form1" method="post" runat="server"> ... <INPUT id="Submit1" type="submit" value="開始上傳" name="Submit1" runat="server"> .... </form> .cs private void Page_Load(object sender, System.EventArgs e) { ...    this.GetPostBackEventReference(Submit1);     //這句很關鍵，有這句才能讓用戶端執行伺服器端事件。    Submit1.Attributes.Add("onclick","abc();");  .... }