Implement back to top handling

2 files changed, 34 insertions, 8 deletions

diff --git a/js/curriculum.js b/js/curriculum.js
index 9b35cc4..a93b2e4 100644
--- a/js/curriculum.js
+++ b/js/curriculum.js
@@ -63,6 +63,13 @@ define(['courses'], function(courses) {
             var text_block = document.createElement('p');
             text_block.textContent = course.description;
             citems.appendChild(text_block);
+
+            var links_block = document.createElement('p');
+            var back_to_top = document.createElement('a');
+            back_to_top.href = '#top';
+            back_to_top.textContent = 'Back to top';
+            links_block.appendChild(back_to_top);
+            citems.appendChild(links_block);
         });
     };
 });
diff --git a/js/main.js b/js/main.js
index d37c228..7ae3fc1 100644
--- a/js/main.js
+++ b/js/main.js
@@ -48,9 +48,9 @@ define(function() {
             loadContent(page, http.responseText);
 
             // focus element when loaded
-            var anchor_id = /^#(.+)/.exec(anchor);
+            var anchor_id = extractHash(anchor);
             if (anchor_id) {
-                var selection = document.getElementById(anchor_id[1]);
+                var selection = document.getElementById(anchor_id);
                 if (selection) {
                     selection.scrollIntoView();
                 }
@@ -61,10 +61,20 @@ define(function() {
         return true;
     }
 
-    function changePageHash(hash) {
-        var m = /#\/([^\/]+)/.exec(hash);
-        if (m) {
-            selectPage(m[1], hash);
+    function extractHash(url) {
+        var m = /#(.+)/.exec(url);
+        return m ? m[1] : '';
+    }
+    function extractPageComponents(url) {
+        var m = /^\/([^\/]+)(.*)$/.exec(extractHash(url));
+        return m ? [m[1], m[2]] : ['', ''];
+    }
+
+    function changePageUrl(url) {
+        var m = extractPageComponents(url);
+        var hash = m.join('');
+        if (hash) {
+            selectPage(m[0], hash);
         } else {
             location.hash = '#/home';
             selectPage('home', hash);
@@ -72,9 +82,18 @@ define(function() {
     }
 
     addEventListener('hashchange', function(ev) {
-        changePageHash(ev.newURL);
+        var anchor = extractHash(ev.newURL);
+        // magic key to jump to the top of the page.
+        if (anchor === 'top') {
+            var pageURL = '#/' + extractPageComponents(ev.oldURL)[0];
+            scrollTo(0, 0);
+            location.replace(pageURL);
+            return;
+        }
+
+        changePageUrl(ev.newURL);
     });
 
     // Tries to load the current page, falling back to "home" for unknown URLs.
-    changePageHash(location.hash);
+    changePageUrl(location.hash);
 });