You can create your own local version of the consolidated Rails API docu-
mentation. Just type the following commands at a command prompt (remem-
bering to start the command window in your Rails environment if you’re using
InstantRails or Locomotive).
rails_apps> rails dummy_app
rails_apps> cd dummy_app
dummy_app> rake rails:freeze:gems
dummy_app> echo >vendor/rails/activesupport/README
dummy_app> rake doc:rails
The last step takes a while. When it finishes, you’ll have the Rails API documen-
tation in a directory tree starting at doc/api. I suggest moving this folder to your
desktop, then deleting the dummy_app tree.