当按下"回车键"时执行Submit事件

<form id="loginForm" name="loginForm" action="login.do" onsubmit="" onkeydown="javascript:keyDown();" method="POST">
</form>

function keyDown() {  
  if(window.event.keyCode == 13){
  //window.event.keyCode=9;//模拟Tab键
  if(check()){
    document.getElementById("loginForm").submit(); //　当按下"回车键"时执行Submit事件
    }         
  }
}