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/elementContains/elementContains.js

@@ -0,0 +1,2 @@
+const elementContains = (parent, child) => parent !== child && parent.contains(child);
+module.exports = elementContains;

test/elementContains/elementContains.test.js

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+const expect = require('expect');
+const elementContains = require('./elementContains.js');
+
+test('elementContains is a Function', () => {
+  expect(elementContains).toBeInstanceOf(Function);
+});