兼容Firefox IE Chrome的onkeydown事件处理方法

<form id="SubscribeForm"> 
<input id="SubscribeEmail" type="text" onkeypress="getEnterEvent(event);return false;"/>                
</form>

function getEnterEvent(ev)
{
var e = window.event || ev;
var keyCode = -1;
if (e.which == null)
keyCode= e.keyCode;    // IE
else if (e.which > 0)
keyCode=e.which;    // All others
if(keyCode==13)
{
formSubmit();//the function we should call            
}
else 
{
$('SubscribeEmail').append(keyCode);
}
}