问如何使用jquery在div中显示表单错误

EN

$("document").ready(function() {
$("#contact_submit").click(function() {
    var first_name = $("#first_name").val();
    var last_name = $("#last_name").val();
    var phone = $("#phone").val();
    var email = $("#email").val();
    var atpos = email.indexOf("@");
    var dotpos = email.lastIndexOf(".");
    var msg = "";

    if(first_name == "") {
        msg+= "First Name is required.<br />";
    }

    if(last_name == "") {
        msg+= "Last Name is required.<br />";
    }

    if(Phone == "") {
        msg+= "Phone Number is required.<br />";
    }

    if (email == "" || atpos < 1 || dotpos < atpos+2 || dotpos+2 > email.length) {
    msg+= "Please enter a valid Email address. <br />";
    }

    if(msg !== "") {
        $("#contact_result").html(msg).show();
    }else {
        // post valuses
    }
});
});