Polyfill insertAdjacentElement and dataset on old browsers

app/javascript/shared/polyfills.js

@@ -3,3 +3,5 @@
 // required by the browsers we support will be included.
 import '@babel/polyfill';
 import 'dom4';
+import './polyfills/insertAdjacentElement';
+import './polyfills/dataset';

app/javascript/shared/polyfills/dataset.js

@@ -0,0 +1,75 @@
+/*
+  @preserve dataset polyfill for IE < 11. See https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/dataset and http://caniuse.com/#search=dataset
+
+  @author ShirtlessKirk copyright 2015
+  @license WTFPL (http://www.wtfpl.net/txt/copying)
+*/
+
+const dash = /-([a-z])/gi;
+const dataRegEx = /^data-(.+)/;
+const hasEventListener = !!document.addEventListener;
+const test = document.createElement('_');
+const DOMAttrModified = 'DOMAttrModified';
+
+let mutationSupport = false;
+
+function clearDataset(event) {
+  delete event.target._datasetCache;
+}
+
+function toCamelCase(string) {
+  return string.replace(dash, function(_, letter) {
+    return letter.toUpperCase();
+  });
+}
+
+function getDataset() {
+  const dataset = {};
+
+  for (let attribute of this.attributes) {
+    let match = attribute.name.match(dataRegEx);
+    if (match) {
+      dataset[toCamelCase(match[1])] = attribute.value;
+    }
+  }
+
+  return dataset;
+}
+
+function mutation() {
+  if (hasEventListener) {
+    test.removeEventListener(DOMAttrModified, mutation, false);
+  } else {
+    test.detachEvent(`on${DOMAttrModified}`, mutation);
+  }
+
+  mutationSupport = true;
+}
+
+if (!test.dataset) {
+  if (hasEventListener) {
+    test.addEventListener(DOMAttrModified, mutation, false);
+  } else {
+    test.attachEvent(`on${DOMAttrModified}`, mutation);
+  }
+
+  // trigger event (if supported)
+  test.setAttribute('foo', 'bar');
+
+  Object.defineProperty(Element.prototype, 'dataset', {
+    get: mutationSupport
+      ? function get() {
+          if (!this._datasetCache) {
+            this._datasetCache = getDataset.call(this);
+          }
+
+          return this._datasetCache;
+        }
+      : getDataset
+  });
+
+  if (mutationSupport && hasEventListener) {
+    // < IE9 supports neither
+    document.addEventListener(DOMAttrModified, clearDataset, false);
+  }
+}

app/javascript/shared/polyfills/insertAdjacentElement.js

@@ -0,0 +1,47 @@
+/*
+  Updated w/ insertAdjacentElement
+  @author Dan Levy @justsml
+  2016-06-23
+
+  Credit: @lyleunderwood - afterend patch/fix
+
+  2011-10-10
+
+  By Eli Grey, http://eligrey.com
+  Public Domain.
+  NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
+*/
+
+function insertAdjacentElement(position, elem) {
+  const _this = this;
+  const parent = this.parentNode;
+  let node, first;
+
+  switch (position.toLowerCase()) {
+    case 'beforebegin':
+      while ((node = elem.firstChild)) {
+        parent.insertBefore(node, _this);
+      }
+      break;
+    case 'afterbegin':
+      first = _this.firstChild;
+      while ((node = elem.lastChild)) {
+        first = _this.insertBefore(node, first);
+      }
+      break;
+    case 'beforeend':
+      while ((node = elem.firstChild)) {
+        _this.appendChild(node);
+      }
+      break;
+    case 'afterend':
+      parent.insertBefore(elem, _this.nextSibling);
+      break;
+  }
+  return elem;
+}
+
+// Method missing in Firefox < 48
+if (!HTMLElement.prototype.insertAdjacentElement) {
+  HTMLElement.prototype.insertAdjacentElement = insertAdjacentElement;
+}