Live Reloading vs. Hot Reloading (aka HMR)
The use of the webpack-dev-server provides "Live Reloading" by default. The difference between live and hot reloading is that live reloading will act similarly to hitting refresh in the browser. Hot reloading will attempt to preserve the state of any props.
See the Webpack document Hot Module Replacement for more details on the concepts of live vs. hot reloading.
The remainder of this document discusses HMR.
Using the Webpacker Webpack setup
If you are using the default Webpacker setup of running the dev server with
bin/webpack-dev-server, see the Webpacker Webpack Dev Server discussion of HMR.
Hot Reloading of Assets For Rails Development
Note, this document is not yet updated for React on Rails v8+. See PR #865 for a detailed example of doing hot reloading using V8+ with Webpack v2. Any volunteers to update this page? See #772 and #361.
- minimal demo here: The most simple and updated hot reloading setup.
- spec/dummy: Simpler setup used for integration testing this gem.
- shakacode/react-webpack-rails-tutorial. Full featured setup using Twitter bootstrap.
This doc might be outdated. PRs welcome!
High Level Strategy
We'll use a Webpack Dev server on port 3500 to provide the assets to Rails, rather than the asset pipeline, and only during development mode. This is configured via the
Procfile.static provides an alternative that uses "static" assets, similar to a production deployment.
Places to Configure (Files to Examine)
- See the Webpack config files. Note, these examples are now setup for using CSS Modules.
- app/views/layouts/application.html.erb: Uses the view helpers
- See the Procfiles: Procfile.hot and Procfile.static. These:
- Start the webpack processes, depending on the mode or HOT or not.
- Start the rails server, setting an ENV value of REACT_ON_RAILS_ENV to HOT if we're hot loading or else setting this to blank.
- Configure the file Rails asset pipeline files:
- Copy the client/server-rails-hot.js to the your client directory.
- Copy the scripts in the top level and client level
Please refer to the examples linked above in
spec/dummy as these code samples might be out of date.