How to only display banner to first time visitor?

Question

I have this text banner on my site. I want it to show it only to new visitors using cookies. I have very little knowledge of JS so please help me how can I show it to only first-time visitors.

I am using it on Discourse-based this Android forum site which is already built on Node.js.

<style>
.top  {
  background: linear-gradient(to right, #141517, #6A9113);
    border-radius: 10px;
    font-size: 20px;
    color: white;
    opacity: 0.9;
    text-align: center;
    padding: 25px;
    line-height: 30px;
    margin: 10px 0px 30px 0px;

}
</style>


<div class="top">
Welcome to the forum. This is demo text.
</div>

Answer 1

Here is the full code... Working demo https://jsfiddle.net/hdas2012/6yjo346k/

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-cookie/1.4.1/jquery.cookie.min.js"></script>

<div class="top">
<h2>You will only see it once</h2>
  Welcome to the forum. This is demo text.
</div>

<script>
    $(document).ready(function(){
      if(!$.cookie('welcomeMsg')){
        $(".top").show();
        $.cookie('welcomeMsg', 'Y', { expires: 365*3 });
      }
    });
</script>
<style>
    .top  {
      background: linear-gradient(to right, #141517, #6A9113);
        border-radius: 10px;
        font-size: 20px;
        color: white;
        opacity: 0.9;
        text-align: center;
        padding: 25px;
        line-height: 30px;
        margin: 10px 0px 30px 0px;
        display: none;
    }
</style>