Improved internal links which use react-router (#3180)

webapp/utils/markdown.jsx

@@ -149,13 +149,13 @@ class MattermostMarkdownRenderer extends marked.Renderer {
             outHref = `http://${outHref}`;
         }
 
-        let output = '<a class="theme markdown__link" ';
+        let output = '<a class="theme markdown__link" href="' + outHref + '" rel="noreferrer"';
 
         // special case for links that are inside the app
         if (outHref.startsWith(global.location.origin)) {
-            output += 'data-link="' + outHref.substring(global.location.origin.length) + '"';
+            output += ' data-link="' + outHref.substring(global.location.origin.length) + '"';
         } else {
-            output += 'href="' + outHref + '" target="_blank" rel="noreferrer"';
+            output += ' target="_blank"';
         }
 
         if (title) {

webapp/utils/text_formatting.jsx

@@ -450,7 +450,13 @@ export function handleClick(e) {
     } else if (hashtagAttribute) {
         Utils.searchForTerm(hashtagAttribute.value);
     } else if (linkAttribute) {
-        browserHistory.push(linkAttribute.value);
+        const MIDDLE_MOUSE_BUTTON = 1;
+
+        if (!(e.button === MIDDLE_MOUSE_BUTTON || e.altKey || e.ctrlKey || e.metaKey || e.shiftKey)) {
+            e.preventDefault();
+
+            browserHistory.push(linkAttribute.value);
+        }
     }
 }