https://www.so-net.ne.jp/shared/js/polyfill/element.prototype.after.js

1//from: https://github.com/jserz/js_piece/blob/master/DOM/ChildNode/after()/after().md
2(function (arr) {
3  arr.forEach(function (item) {
4    if (item.hasOwnProperty('after')) {
5      return;
6    }
7    Object.defineProperty(item, 'after', {
8      configurable: true,
9      enumerable: true,
10      writable: true,
11      value: function after() {
12        var argArr = Array.prototype.slice.call(arguments),
13          docFrag = document.createDocumentFragment();
14
15        argArr.forEach(function (argItem) {
16          var isNode = argItem instanceof Node;
17          docFrag.appendChild(isNode ? argItem : document.createTextNode(String(argItem)));
18        });
19
20        this.parentNode.insertBefore(docFrag, this.nextSibling);
21      }
22    });
23  });
24})([Element.prototype, CharacterData.prototype, DocumentType.prototype]);