Revert "remove extra js"

This reverts commit ebb26eab.

theme/js/loadhtmlslides.js

+// Modified from markdown.js from Hakim to handle external html files
+(function () {
+    /*jslint loopfunc: true, browser: true*/
+    /*globals alert*/
+    'use strict';
+
+    var querySlidingHtml = function () {
+        var sections = document.querySelectorAll('[data-html]'),
+            section, j, jlen;
+
+        for (j = 0, jlen = sections.length; j < jlen; j++) {
+            section = sections[j];
+
+            if (section.getAttribute('data-html').length) {
+
+                var xhr = new XMLHttpRequest(),
+                    url = section.getAttribute('data-html'),
+                    cb = function () {
+                        if (xhr.readyState === 4) {
+                            if (xhr.status >= 200 && xhr.status < 300) {
+                                section.innerHTML = xhr.responseText;
+                            } else {
+                                section.outerHTML = '<section data-state="alert">ERROR: The attempt to fetch ' + url + ' failed with the HTTP status ' + xhr.status + '. Check your browser\'s JavaScript console for more details.</p></section>';
+                            }
+                        }
+                    };
+
+                xhr.onreadystatechange = cb;
+
+                xhr.open('GET', url, false);
+                try {
+                    xhr.send();
+                } catch (e) {
+                    alert('Failed to get file' + url + '.' + e);
+                }
+            }
+        }
+    };
+
+    querySlidingHtml();
+})();