javascript 获取焦距触发按钮事件

  <script type="text/javascript"> 
 
    document.onkeydown=function(e)
    {
    e=e?e:window.event;
    var keyCode=e.which?e.which:e.keyCode;
    if(keyCode==13)
    {
         if(document.getElementById("tbxName").value == "")
                {
                    document.getElementById("tbxName").focus();
                } 
                else if(document.getElementById("tbxPassword").value == "")
                {
                    document.getElementById("tbxPassword").focus();
                }
                else               
                {          
                    document.getElementById("Button1").focus();
                    document.getElementById("Button1").click();
                }
         return false;

    }
    }

  </script>