<form method="post" action="" id="home-sign-up-form">
    <input type="text" name="suFirstName" placeholder="First Name" class="text-input-minor" id="sign-up-first-name-text-input">
    <input type="text" name="suLastName" placeholder="Last Name" class="text-input-minor" id="sign-up-last-name-text-input">
    <input type="text" name="suEmail" placeholder="Email" class="text-input-minor" id="sign-up-email-text-input">
    <input type="password" name="suPassword" placeholder="Password" class="text-input-minor" id="sign-up-password-text-input">
    <input type="password" name="suConfirmPassword" placeholder="Confirm Password" class="text-input-minor" id="sign-up-confirm-password-text-input">
    <input type="text" name="suDisplayName" placeholder="Display Name (you can change this later)" class="text-input-minor" id="sign-up-display-name-text-input">
    <br><font class="text-error" id="sign-up-error-text"></font><br>
    <label><input type="checkbox" name="suRememberMe" value="yes" id="sign-up-remember-me-checkbox"><font id="sign-up-remember-me-text">Remember me</font></label>
    <input name="signUp" type="submit" value="Sign Up" id="sign-up-submit">
</form>

if (validForm)
{
    console.log("valid form");
    console.log(JSON.stringify($('#home-sign-up-form')[0].seriaize()));
    $.ajax(
    {
        type:'POST',
        url:'form-submit.php',
        data:$('#home-sign-up-form')[0].serialize(),
        success:function(response)
        {
            $suForm.hide();
            $tosppText.hide();
            $mailSentIcon.show();
            $emailSentText.show();
            $emailSentTextEmail.text($suEmail);
            $suBox.css("padding-left", "10px");
            $suBox.css("padding-right", "10px");
        }
    });
}

<?php require 'dbconnect.php'; ?>
if (isset($_POST['suEmail']))
{
    echo "<script type='text/javascript'>alert('got');</script>";
    $suFirstName = mysqli_real_escape_string($_POST['suFirstName']);
    $suLastName = mysqli_real_escape_string($_POST['suLastName']);
    $suEmail = mysqli_real_escape_string($_POST['suEmail']);
    $suPassword = mysqli_real_escape_string($_POST['suPassword']);
    $suDisplayName = mysqli_real_escape_string($_POST['suDisplayName']);
    $code = substr(md5(mt_rand()),0,15);

    $query = $connection->query("INSERT INTO users (firstName,lastName,email,password,displayName,confirmCode,verified)Values('{$suFirstName}','{$suLastName}','{$suEmail}','{$suPassword}','{$suDisplayName}','{$confirmCode},'{$verified}')");
}