JSFiddle - React, Tailwind, and code Playground

HTML

<form>
  <input name="field-a" value="Some value for field A" />
  <input name="field-b" value="Some value for field B" />
  <input type="submit" />
</form>

JavaScript

document.querySelector('form').addEventListener('submit', (e) => {
  const formData = new FormData(e.target);
  alert(formData.get('field-a'));
  alert(formData.get('field-b'));
  e.preventDefault();
});