Set once: true for all addEventListener in contact.js so not to waste CPU cycels.

assets/js/contact.js

@@ -7,12 +7,11 @@
 
   'use strict';
 
-  const body = document.querySelector('body');
   const form = document.querySelector('.contact-form');
   const button = form.querySelector('[type=submit]');
   const action = form.getAttribute('data-protect');
 
-  function activateForm() {
+  const activateForm = function () {
     form.setAttribute('action', action);
     button.removeAttribute('disabled');
   }
@@ -21,15 +20,15 @@
   form.classList.remove('hidden');
 
   // Wait for a mouse to move, indicating they are human.
-  body.addEventListener('mousemove', () => activateForm());
+  document.body.addEventListener('mousemove', activateForm, { once: true });
   // Wait for a touch move event, indicating that they are human.
-  body.addEventListener('touchmove', () => activateForm());
+  document.body.addEventListener('touchmove', activateForm, { once: true });
   // A tab or enter key pressed can also indicate they are human.
-  body.addEventListener('keydown', function (e) {
+  document.body.addEventListener('keydown', function (e) {
     if ((e.key === 'Tab') || (e.key === 'Enter')) {
       activateForm();
     }
-  });
+  }, { once: true });
 
   // Mark the form as submitted.
   button.addEventListener('click', () => form.classList.add('js-submitted'));