回车提交表单
<input name="passwd" type="password" value="" onkeydown="return enterSubmit(event);"/>
function enterSubmit(e)
{
var keynum = 0;
if(window.event){//IE
keynum = e.keyCode;
}else if(e.which){
keynum = e.which;
}
if(keynum == 13){
Submit();
return false;
}
}