JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="event_content" cols="60" rows="20">
This text area could be full of information www.london2012.com 
And might contain upto 5 links that all need updating. 
Visit www.rio2016.org 
Amazon web: http://www.amazon.com
Secure Google: https://www.google.com
</textarea>

JavaScript

$('#event_content').val(
  $('#event_content').val().replace(/\b(http(s|):\/\/|)(www\.\S+)/ig,
    "<a href='http\$2://\$3' target='_blank'>\$3</a>"));