JSFiddle - React, Tailwind, and code Playground

HTML

<title>Red Bull Quest BYPASS BY STRIK3</title>
<script language="javascript" type="text/javascript">
function randomString() {
	var chars = "XCKFHLMNVPATR";
	var string_length = 2;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
	}
	document.randform.code.value = randomstring ;
}
 function randomStringa() {
	var chars = "347743";
	var string_length = 6;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
	}
      randomString() ;
	document.randform.code.value = document.randform.code.value + randomstring ;
    document.randform.code.value = document.randform.code.value.split('').sort(function(){return 0.5-Math.random()}).join('');
}
</script>
<body>
    <div class="redbull_globalnav">
    </div>
    <div class="container">
        <section id="redeem" class="redeem">
            <div class="section-inner">
                 <h1>
                <img class="svg logo-quest" src="http://quest.redbull.com/assets/images/redbullquest.svg" width="500" alt="Red Bull Quest" /></a>
                <img class="logo-destiny" src="http://quest.redbull.com/assets/images/destiny_logo.png" width="375" alt="Destiny" />
       >By Strik3<     </h1>

                <div class="error"></div>
                <form name="randform" target="_blank" action="http://quest.redbull.com/us/en/claim" method="post">
                    <p class="form-control">
                        <input type="text" name="code" class="redeem__code" id="code" autocomplete="off" maxlength="8" value="" tabindex="0" onClick="randomStringa();" required />
                    </p>
                    <script>
                        randomStringa();
                    </script>
                    <p class="form-control form-control--terms">
                        <label for="terms"...

JavaScript

window.onload = randomStringa();
function randomString() {
	var chars = "XCKFHLMNVPATR";
	var string_length = 2;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
	}
	document.randform.code.value = randomstring ;
}
 function randomStringa() {
	var chars = "347743";
	var string_length = 6;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
	}
      randomString() ;
	document.randform.code.value = document.randform.code.value + randomstring ;
   document.randform.code.value = document.randform.code.value.split('').sort(function(){return 0.5-Math.random()}).join('');
}