JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" size="50" style="padding:10px 20px" />

JavaScript

$('input').change( function() {
	s = $(this).val();
  if (s && !s.match(/^[a-zA-Z]+:\/\//))
  {
      s = 'http://' + s;
      console.log(s)
      $(this).val(s)
  }
});