Factor out the scrollOrAction pattern (#106)

frontend/src/aspects/exploration.ts

@@ -42,20 +42,13 @@ channel.on('currentRoute', (route, panel) => {
 
 mainRouter.on('route:explore', () => {
     ensureSources();
-    const cid = sourceListPanel.cid;
-    if (explorer.has(cid)) {
-        explorer.scroll(cid);
-    } else {
-        explorer.reset(sourceListPanel);
-    }
+    explorer.scrollOrAction(
+        sourceListPanel.cid,
+        () => explorer.reset(sourceListPanel)
+    );
 });
 
-router.on('route', (route, [serial]) => {
-    const state = browserHistory.state;
-    // state can only be a string if we made it so.
-    if (isString(state) && explorer.has(state)) {
-        explorer.scroll(state);
-    } else {
-        executeRoute(route, controller, serial);
-    }
-});
+router.on('route', (route, [serial]) => explorer.scrollOrAction(
+    browserHistory.state,
+    () => executeRoute(route, controller, serial)
+));

frontend/src/explorer/explorer-view.ts

@@ -214,6 +214,19 @@ export default class ExplorerView extends View {
         return this;
     }
 
+    /**
+     * Scroll to a panel if present, otherwise execute an action of choice.
+     * Useful in routing.
+     */
+    scrollOrAction(cid, action: () => void): this {
+        if (isString(cid) && this.has(cid)) {
+            this.scroll(cid);
+        } else {
+            action();
+        }
+        return this;
+    }
+
     /**
      * Remove the topmost panel from the stack at position. Returns the deleted panel.
      * @param position The indes of the stack to remove the panel from