don't cache files in static/custom or nbextensions

always rely on 304 for cache content there

IPython/html/base/handlers.py

@@ -320,7 +320,7 b' class AuthenticatedFileHandler(IPythonHandler, web.StaticFileHandler):'
     
     def set_headers(self):
         super(AuthenticatedFileHandler, self).set_headers()
-        # disable browser caching, rely in 304 replies for savings
+        # disable browser caching, rely on 304 replies for savings
         if "v" not in self.request.arguments:
             self.add_header("Cache-Control", "no-cache")
     
@@ -394,11 +394,14 b' class FileFindHandler(web.StaticFileHandler):'
     
     def set_headers(self):
         super(FileFindHandler, self).set_headers()
-        # disable browser caching, rely in 304 replies for savings
-        if "v" not in self.request.arguments:
+        # disable browser caching, rely on 304 replies for savings
+        if "v" not in self.request.arguments or \
+                any(self.request.path.startswith(path) for path in self.no_cache_paths):
             self.add_header("Cache-Control", "no-cache")
     
-    def initialize(self, path, default_filename=None):
+    def initialize(self, path, default_filename=None, no_cache_paths=None):
+        self.no_cache_paths = no_cache_paths or []
+        
         if isinstance(path, string_types):
             path = [path]
         

IPython/html/notebookapp.py

@@ -171,6 +171,10 b' class NotebookWebApplication(web.Application):'
             static_path=ipython_app.static_file_path,
             static_handler_class = FileFindHandler,
             static_url_prefix = url_path_join(base_url,'/static/'),
+            static_handler_args = {
+                # don't cache custom.js
+                'no_cache_paths': [url_path_join(base_url, 'static', 'custom')],
+            },
             version_hash=version_hash,
             
             # authentication
@@ -218,8 +222,12 b' class NotebookWebApplication(web.Application):'
         handlers.extend(load_handlers('services.sessions.handlers'))
         handlers.extend(load_handlers('services.nbconvert.handlers'))
         handlers.extend(load_handlers('services.kernelspecs.handlers'))
+        
         handlers.append(
-            (r"/nbextensions/(.*)", FileFindHandler, {'path' : settings['nbextensions_path']}),
+            (r"/nbextensions/(.*)", FileFindHandler, {
+                'path': settings['nbextensions_path'],
+                'no_cache_paths': ['/'], # don't cache anything in nbextensions
+            }),
         )
         # register base handlers last
         handlers.extend(load_handlers('base.handlers'))