JSFiddle - React, Tailwind, and code Playground

by Alexandre Simoes

HTML

<form name="theForm" action="##" onsubmit="return validateForm()" method="post">
  <div class="col-xs-4">
    <div style="text-align:left;" class="form-group">
      <label for="credit0_number">Credit Card Number</label>
      <input type="number" class="inp form-control" id="credit0_number" name="credit0[number]">
    </div>
    <input type="submit" value="Submit" />
  </div>
</form>

JavaScript

function validateForm() {
  var regex = /^\d{16}$/;
  var assert = regex.test(credit0_number.value)

  return assert;
}