JSFiddle - React, Tailwind, and code Playground

HTML

<div id="register" class="grid_12">
    		<div id="insideregister" class="grid_12margin">
            <div class="constrain">
			    
                <div class="elegantaeroregister registermargin">
                <h1>New Customer Registration.</h1>
                <h6>Please fill in the form below.</h6>
                
                <h3>Please Read - We are currently experiencing a number of issues with this form.</h3><p> If the page refreshes on submit please make sure that your password is at least 6 characters long and includes 1 uppercase letter and 1 number (e.g. Password5). Also make sure the phone number is in this format: 01223750000. On this note, we would like to apologise for any inconvenience this may cause and if you are still experiencing problems, please use the support tab or call us on 01223750000. </p>
<% if error %><p class='error'>An internal error occurred! Please try again later</p><% end %>

<form accept-charset='utf-8' method='post' name="form" action='register' class="registerform" onsubmit="return validate_form()">
<h3 class="registernospace">Contact Information</h3>
<table>
<tbody>
<tr><th class="registerrowspace">Salutation</th><td class="registerrowspace"> <%= field('salutation') %> </td></tr>
<tr><th class="registerrowspace">First Name(s)</th><td class="registerrowspace"><%= field('name:first') %></td></tr>
<tr><th class="registerrowspace">Surname</th><td class="registerrowspace"><%= field('name:last') %></td></tr>
<tr><th class="registerrowspace">Organisation Type</th><td class="registerrowspace registeroraganisationtype"> <%= field('org-type') %> </td></tr>
<tr><th class="registerrowspace">Organisation Name</th><td class="registerrowspace"><%= field('org-name') %></td></tr>
<script type='text/javascript'>
toggle_org_name();
</script>
<tr><th class="registerrowspace">First Line of Address</th><td class="registerrowspace"><%= field('address') %></td></tr>
<tr><th class="registerrowspace">Second Line of Address</th><td...

JavaScript

<script type="text/javascript">
  function check_form()
  {
    var passw = document.getElementById('password1').value;
    /*if(passw.value != ""/* && form.password.value == form.pwd2.value) {*/
      if(passw.value.length < 6 ) {
        alert("Error: Password must contain at least six characters!");
        form.password.focus();
        return false;
   
      }/*}*/
    return true;
  }
</script>

<script type='text/javascript'>
function validate_form() {	
  // Check the terms and conditions have been accepted.
  var checkbox = document.getElementsByName('terms-accepted').item(0);
  if(!checkbox.checked) {
    alert('You cannot register unless you accept our terms and conditions.');
    return false;
  }
  
  //passwordtry
  /*var pass = document.getElementsByName('password');
  if(pass.length < 6){
	  alert("Please enter valid password");
	  return false;
  
  }*/

  // Must have a county entered. Could be NA if not applicable.
  if(document.getElementById('address:county-input-0').value == '') {
    alert('Please enter your county, or enter "NA" if not applicable.');
    return false;
  }

  var correct_phone_format_desc = "The Telephone Number should be formatted:\n'+CCC.NNNNNNNNNN'\nwhere CCC is your country code and NN.. is your phone number.\ne.g. '+34.120120120'.";
  var default_phone = document.getElementById('phone:default-input-0').value;
  if(!default_phone.match(/^[+.0-9 \-]+$/)) {
    alert(correct_phone_format_desc);
    return false;
  }
  if(document.getElementById('address:country-select-0').value == 'GB') {
    // Check that this looks like a UK postcode.
    var postcode = document.getElementById('address:postcode-input-0').value;
    if(postcode.length < 5) {
      alert("The postcode entered is not long enough.");
      return false;
    }

    if(!postcode.match(/[a-zA-Z]/)) {
      if(!postcode.match(/^[a-zA-Z]/)) {
        alert("A postcode must begin with a letter.");
        return false;
      }

      alert("A postcode must...