JSFiddle - React, Tailwind, and code Playground

by wictor

HTML

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
<input type="text" value="" id="txt_serial">
<input type="button" value="gerar" id="botao_serial">

JavaScript

function geraSerial() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 6; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return "wf2017" + text;
}
$(function(){
	$('#botao_serial').click(function(){
  		$('#txt_serial').val(geraSerial());
  });
});