Form Validation

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/foundation/5.5.1/css/foundation.min.css">
<script src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/133687/mailcheck.min.js"></script>
<div class="input-wrapper">
    <input type="text" class="text-field" placeholder="First Name" name="firstName" id="firstName" value=""></input>
    <div class="warning"></div>
</div>
<div class="input-wrapper">
    <input type="text" class="text-field" placeholder="Last Name" name="lastName" id="lastName" value=""></input>
    <div class="warning"></div>
</div>
<div class="input-wrapper">
    <input type="text" class="text-field" placeholder="Email Address" name="emailAddress" id="emailAddress"></input>
    <div class="warning"></div>
</div>
<div id="birthday">
    <select id="day" name="day">
        <option value="#">Day</option>
    </select>
    <select id="month" name="month" class="reg_birthdate">
        <option value="#">Month</option>
    </select>
    <select id="year" name="year" class="reg_birthdate">
        <option value="#">Year</option>
    </select>
</div>
<div class="warning"></div>
<div class="input-wrapper">
    <input type="password" class="text-field" placeholder="Password" name="password" id="password" value=""></input>
    <input type="password" class="text-field" placeholder="Confirm Password" name="confirmPassword" id="confirmPassword" value=""></input>
    <div class="warning"></div>
</div>

<input type="submit" id="submit" value="Submit" class="button">

CSS

body {
    padding: 10px;
}
#day, #month, #year {
    width: 32.7%;
}
.required-field {
    border-color: orange !important;
    border-width: 2px !important;
}
.success-field {
    border-color: green !important;
    border-width: 2px !important;
}
.error-field {
    border-color: red !important;
    border-width: 2px !important;
}
.warning {
    background-color: lightgray;
    border-radius: 0 0 5px 5px;
    display: none;
    margin: -16px 0 16px 0;
    padding: 0.25em 0.5em;
}
.warning span {
    font-size: 0.8rem;
}

input[type="password"] {
    width: 49.5%;
    display: inline-block;
}

JavaScript

//POPULATE DROPDOWNS
var d = new Date();
var day = $('#day');
var month = $('#month');
var year = $('#year');
var months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];

for (var i = 1; i <= 31; i++) {
    var opt = i;
    var el = document.createElement("option");
    el.textContent = opt;
    el.value = opt;
    day.append(el);
}

for (var i = 1; i <= 12; i++) {
    var opt = i;
    var el = document.createElement("option");
    el.textContent = months[i - 1];
    el.value = opt;
    month.append(el);
}

for (var i = (d.getFullYear() - 18); i > (d.getFullYear() - 100); i--) {
    var opt = i;
    var el = document.createElement("option");
    el.textContent = opt;
    el.value = opt;
    year.append(el);
}

var alphaRegex = new RegExp(/[a-zA-Z\s]/g);
var numericRegex = new RegExp(/([0-9])/g);
var specialCharactersRegex = new RegExp(/([^A-Za-z0-9\s]+)/g);
var emailRegex = new RegExp(/^[a-z0-9._-]+@[a-z0-9.-]+\.[a-z]{2,6}$/i);

var alphaCheck = function (input) {
    var regex = input.match(alphaRegex);
    if (regex !== null) {
        return false;
    }
};

var numericCheck = function (input) {
    var regex = input.match(numericRegex);
    if (regex !== null) {
        return false;
    }
};


var emailCheck = function (input) {
    input.replace(/ /g, '');
    var regex = input.match(emailRegex);
    if (regex === null && input.length > 0) {
        return false;
    }
};

var checkMail = function(field){
    $('#' + field.ID).on('blur', function() {
      $(this).mailcheck({
        suggested: function(element, suggestion) {
          console.log(suggestion.full);
          var suggestEmail = "Did you mean... ";
          showErrorMessage(field, suggestEmail + '<a>' +suggestion.full+ '</a>');
        },
        empty: function(element) {
          //console.log(element)
        }
      });
    });
};

var dateCheck = function (d, m, y, field) {
    var ymd = new Date(y, m - 1, d);
    var today = new Date();

    if...