JSFiddle - React, Tailwind, and code Playground

HTML

<script src='https://raw.githack.com/eKoopmans/html2pdf/master/dist/html2pdf.bundle.js'></script>
<form id="form" class="ui form" action="/PageTwo" method="POST" onsubmit="checkForMissingFields(event)">
<input type="text" id="Name">
<button>
submit
</button>

</form>

JavaScript

// var form = getElementById('form')
function GenPDF() {
  var name = document.getElementById('Name').value;
  var element = document.getElementById('form');
  var opt = {
    margin: 1,
    filename: name + '.pdf',
    image: {
      type: 'png',
      quality: 0.98
    },
    html2canvas: {
      scale: 2
    },
    jsPDF: {
      unit: 'in',
      format: 'letter',
      orientation: 'landscape'
    }
  };


  html2pdf().set(opt).from(element).save();

}

function checkForMissingFields(event) {
  if (document.getElementById("Name").value.length == 0) {
    event.preventDefault();
    alert("Name field cannot be blank");
    return false;
  } else {
    GenPDF();
    return true;

  }
}