Form Submit - Find a rom

<script>
  (function validateForm() {
    var a = document.querySelector('#firstname').value,
      b = document.querySelector('#lastname').value,
      c = document.querySelector('#email').value,
      d = document.querySelector("[name='Tour[Candidate][phone-raw]']").value,
      e = document.querySelector('#date').value,
      f = document.querySelector('#job').value;
    if (!a || !b || !c || !d || !e || !f) {
      console.log('fields are empty!');
    } else {
      dataLayer.push({
        event: 'find_a_room_form_submit',
        firstName: a,
        lastName: b,
        email: c,
        phone: d,
        dob: e,
        job: f,
      });
    }
  })();
</script>