Clean up some code in the JS server, add comments

Author: zpao

server.js

@@ -23,9 +23,15 @@ app.set('port', (process.env.PORT || 3000));
 app.use('/', express.static(path.join(__dirname, 'public')));
 app.use(bodyParser.json());
 app.use(bodyParser.urlencoded({extended: true}));
+
+// Additional middleware which will set headers that we need on each request.
 app.use(function(req, res, next) {
-    //set permissive CORS header
+    // Set permissive CORS header - this allows this server to be used only as
+    // an API server in conjunction with something like webpack-dev-server.
     res.setHeader('Access-Control-Allow-Origin', '*');
+
+    // Disable caching so we'll always get the latest comments.
+    res.setHeader('Cache-Control', 'no-cache');
     next();
 });
 
@@ -35,7 +41,6 @@ app.get('/api/comments', function(req, res) {
       console.error(err);
       process.exit(1);
     }
-    res.setHeader('Cache-Control', 'no-cache');
     res.json(JSON.parse(data));
   });
 });
@@ -61,7 +66,6 @@ app.post('/api/comments', function(req, res) {
         console.error(err);
         process.exit(1);
       }
-      res.setHeader('Cache-Control', 'no-cache');
       res.json(comments);
     });
   });