diff --git a/static/index.js b/static/index.js
index 36f6d4a67..88634ee63 100644
--- a/static/index.js
+++ b/static/index.js
@@ -12,14 +12,16 @@ window.onload = function() {
         cacheDir = path.join(cacheDir, 'root');
       }
 
-      // This sets require.extensions['.coffee'].
+      // Setup caching of .coffee files
       require('coffee-cash').register(path.join(cacheDir, 'coffee'));
 
+      // Set up caching of source maps for generated stack traces
       require('coffeestack').setCacheDirectory(path.join(cacheDir, 'coffee', 'source-maps'));
 
+      // Setup caching of .cson files
       require('season').setCacheDir(path.join(cacheDir, 'cson'));
 
-      // This redefines require.extensions['.js'].
+      // Setup caching of .js files that start with "use 6to5"
       require('../src/6to5').register(path.join(cacheDir, 'js'));
     }