Allow selecting elevation level with up/down buttons

src/index.js

@@ -208,6 +208,22 @@ document.querySelector('#roll-dice').addEventListener('click', () => {
   });
 });
 
+document.querySelectorAll('.select-elevation button').forEach(el => el.addEventListener('click', () => {
+  const current = document.querySelector('.select-elevation input:checked');
+  const siblingMethod = `${el.classList.contains('up') ? 'previous' : 'next'}ElementSibling`;
+  let next = current;
+
+  do {
+    next = next[siblingMethod];
+  } while (next !== null && !next.matches('input'));
+
+  if (next) {
+    next.checked = true;
+    const event = new Event('change', { value: next.value });
+    next.dispatchEvent(event);
+  }
+}));
+
 document.querySelectorAll('[name="select-elevation"]').forEach(el => {
   el.addEventListener('change', function (e) {
     document.querySelector('object').contentDocument.querySelector('.gameboard').dataset.viewElevation = this.value;