Fixed #155: Make header auto-anchors optional. While doing that, also…

… updated marked.js to markedjs/marked@613bf6a. Need updated translations for new text.

src/_locales/en/messages.json

@@ -333,5 +333,15 @@
   "new_changelist_items": {
     "message": "NEW",
     "description": "Used to highlight the part of the changelist that is new"
+  },
+  "options_page__header_anchors_enabled_label": {
+    "message": "<b>Enable automatic header anchors.</b>",
+    "description": "Label for the checkbox that enables the automatic header anchors feature. This means that an 'anchor' is created at every heading (H1, H2, etc.) in the user's Markdown. The user can then create links that will jump to these anchors, like in the table of contents of a document."
+  },
+  "options_page__header_anchors_enabled_1": {
+    "message": "This is great if you want to put a table of contents or other internal links into your content. <a href=\"https://github.com/adam-p/markdown-here/wiki/Tips-and-Tricks#wiki-header-anchors\" target=\"_blank\">Learn about how to use it in the MDH wiki.</a>"
+  },
+  "options_page__header_anchors_enabled_2": {
+    "message": "It's disabled by default because it <a href=\"https://github.com/adam-p/markdown-here/issues/155\" target=\"_blank\">creates visual noise in Thunderbird</a>. (And most people probably won't use the feature.)"
   }
 }

src/common/markdown-render.js

@@ -32,7 +32,48 @@ function markdownRender(mdText, userprefs, marked, hljs) {
             .replace(/\{urlmathcode\}/ig, encodeURIComponent(mathcode));
   }
 
+  // Hook into some of Marked's renderer customizations
+  var markedRenderer = new marked.Renderer();
+
+  var sanitizeLinkForAnchor = function(text) {
+    return text.toLowerCase().replace(/[^\w]+/g, '-');
+  };
+
+  var defaultHeadingRenderer = markedRenderer.heading;
+  markedRenderer.heading = function (text, level, raw) {
+    if (userprefs['header-anchors-enabled']) {
+      // Add an anchor right above the heading. See MDH issue #93.
+      var sanitizedText = sanitizeLinkForAnchor(text);
+      var anchorLink = '<a href="#" name="' + sanitizedText + '"></a>';
+      return '<h' + level + '>' +
+             anchorLink +
+             text +
+             '</h' + level + '>\n';
+    }
+    else {
+      return defaultHeadingRenderer.call(this, text, level, raw);
+    }
+  };
+
+  var defaultLinkRenderer = markedRenderer.link;
+  markedRenderer.link = function(href, title, text) {
+    // Added to fix MDH issue #57: MD links should automatically add scheme.
+    // Note that the presence of a ':' is used to indicate a scheme, so port
+    // numbers will defeat this.
+    href = href.replace(/^(?!#)([^:]+)$/, 'http://$1');
+
+    if (userprefs['header-anchors-enabled']) {
+      // Add an anchor right above the heading. See MDH issue #93.
+      if (href.indexOf('#') === 0) {
+        href = '#' + sanitizeLinkForAnchor(href.slice(1).toLowerCase());
+      }
+    }
+
+    return defaultLinkRenderer.call(this, href, title, text);
+  };
+
   var markedOptions = {
+    renderer: markedRenderer,
     gfm: true,
     pedantic: false,
     sanitize: false,