Add 4 new browser snippets

triggerEvent - trigger an event on an element, insertAfter & insertBefore - parse and insert HTML after or before an element respectively, elementContains - checks if an element contains another element

test/insertAfter/insertAfter.test.js

@@ -0,0 +1,6 @@
+const expect = require('expect');
+const insertAfter = require('./insertAfter.js');
+
+test('insertAfter is a Function', () => {
+  expect(insertAfter).toBeInstanceOf(Function);
+});