JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
<textarea id="myText" rows="10" cols="50"></textarea>
<br>
<button id="check">
  Check
</button>

JavaScript

$(document).ready(function() {
  $('#check').click(function() {
    var content = $('#myText').val();
    var pattern = new RegExp("http:");
    var result = '';

    result = pattern.test(content) ? 'Invalid' : 'valid';
    alert(result);
  })
})