兼容IE火狐的Enter回车快捷事件

//回车提交事件
document.onkeydown = function (event) {
e = event ? event : (window.event ? window.event : null);
if (e.keyCode==13) {
var account = $.trim($("#txtAccount").val());
if (account == "") {
alert("账号不能为空");
$("#txtAccount").focus();
return;
}

var pwd = $.trim($("#txtPass").val());
if (pwd == "") {
alert("密码不能为空");
$("#txtPass").focus();
return;
}
}
}