How to add multiple values via prompt to textarea without removing and changing other texts?

I created this fiddle so that you can see the struggle I have.

My HTML

<form action="" method="post" role="form" name="my-form-name">

<button class="html-button">Link me</button>

<textarea name="x" id="post-text" rows="17" required="required"></textarea>

<button type="submit" class="submit-button-form">submit form</button>

</form>

JS:

$(".html-button").on("click", function () {
    var urls = prompt("Add a link", "http://");
    var setText = $("#post-text").val(urls);
// Adding prompt text into my input field
    $("#post-text").val(urls);
                            });

This code works, but it only works once. Meaning: if I add a hyperlink it works the first time, but when I want to add another link, it doesn't insert it. Instead, it just changes whatever I had put in first + the additonal plain text I am adding to the textarea.

My question: how can I make this link addition independent of what I type in the textarea (plain text) and make sure that I can add more links without it changing the other ones in the textarea?

Fiddle: https://jsfiddle.net/vaxqsztj/1/

Solution

You need to append data instead of replacing

$("#post-text").val(urls);   <-- here you're replacing data with url only

instead you need to add previous text along with url

var setText = $("#post-text").val(urls);
$("#post-text").val(setText + urls);   <-- adding url along with previous value

$(".html-button").on("click", function() {
  var urls = prompt("Add a link", "http://");
  var setText = $("#post-text").val();
  // Adding prompt text into my input field
  $("#post-text").val(setText + urls);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form action="" method="post" role="form" name="my-form-name">
  <button class="html-button" type='button'>Link me</button>
  <textarea name="x" id="post-text" rows="17" required="required"></textarea>
  <button type="submit" class="submit-button-form">submit form</button>
</form>