Make package UMD (Univeral Module Definition) compatible

Wrap main logic so that it can be loaded by CommonJS (node and
bundlers like webpack), AMD (RequireJS), and browser script.

UMD template:
https://github.com/ForbesLindesay/umd/blob/master/template.js

Author: remarkablemark

index.js

@@ -1,32 +1,58 @@
-'use strict';
-
-/**
- * Module dependencies.
- */
-var domToReact = require('./lib/dom-to-react');
-var htmlToDOM;
-
-/**
- * Detect environment.
- */
-
-/** Client (Browser). */
-if (typeof window !== 'undefined' && this === window) {
-    htmlToDOM = require('./lib/html-to-dom-client');
-
-/** Server (Node). */
-} else {
-    htmlToDOM = require('./lib/html-to-dom-server');
-}
-
-/**
- * Convert HTML to React.
- *
- * @param  {String}   html              - The HTML.
- * @param  {Object}   [options]         - The additional options.
- * @param  {Function} [options.replace] - The replace method.
- * @return {ReactElement|Array}
- */
-module.exports = function(html, options) {
-    return domToReact(htmlToDOM(html), options);
-};
+;(function(factory) {
+
+    // CommonJS
+    if (typeof exports === 'object' && typeof module !== 'undefined') {
+        module.exports = factory();
+
+    // RequireJS (AMD)
+    } else if (typeof define === 'function' && define.amd) {
+        define([], factory());
+
+    // Browser (script tag)
+    } else {
+        var root;
+        if (typeof window !== 'undefined') {
+            root = window;
+        } else if (typeof global !== 'undefined') {
+            root = global;
+        } else if (typeof self !== 'undefined') {
+            root = self;
+        } else {
+            // works provided we're not in strict mode
+            root = this;
+        }
+
+        // define namespace
+        root.HTMLReactParser = factory();
+    }
+
+})(function() {
+
+    var domToReact = require('./lib/dom-to-react');
+    var htmlToDOM;
+
+    // client (browser)
+    if (typeof window !== 'undefined' && this === window) {
+        htmlToDOM = require('./lib/html-to-dom-client');
+
+    // server (node)
+    } else {
+        htmlToDOM = require('./lib/html-to-dom-server');
+    }
+
+    /**
+     * Convert HTML string to React elements.
+     *
+     * @param  {String}   html              - The HTML.
+     * @param  {Object}   [options]         - The additional options.
+     * @param  {Function} [options.replace] - The replace method.
+     * @return {ReactElement|Array}
+     */
+    function HTMLReactParser(html, options) {
+        return domToReact(htmlToDOM(html), options);
+    }
+
+    // source
+    return HTMLReactParser;
+
+});