How to integrate React with Rails?

React, a popular JavaScript library for building user interfaces, can be seamlessly integrated with Ruby on Rails, a robust web application framework. Here’s a brief overview of how to accomplish this integration:

1. Webpacker: With Rails 5.1 and above, Webpacker became the official way to integrate frontend tools and frameworks, including React. Start by adding Webpacker to your Rails application using the command `rails webpacker:install`. To add React support, you would then run `rails webpacker:install:react`.

2. React Components: After the setup, you’ll find that Rails can generate React components inside the `app/javascript` folder. You can use the `javascript_pack_tag` in your Rails views to include these components.

3. react-rails Gem: Another popular approach is to use the `react-rails` gem. Once added to your Gemfile and bundled, this gem provides a Rails way to create React components and also offers helper methods to render them directly in your views.

4. API Mode: For a more decoupled approach, Rails can be set up in API mode to serve as a backend, while React can be set up on the frontend using tools like Create React App. The frontend and backend communicate via API calls. This setup promotes a clear separation of concerns, but requires additional configuration, like handling CORS.

5. State Management & Routing: When building complex applications, you might consider integrating state management libraries like Redux and routing libraries like React-Router. These tools further enhance the React experience within Rails.

6. Deployment: Deploying a Rails app with integrated React might require some additional steps, especially if assets are compiled with Webpack. Platforms like Heroku have buildpacks that can ease this process.

Integrating React with Rails provides developers with the best of both worlds – the versatility of React’s frontend capabilities combined with the power and convention-over-configuration paradigm of Rails. Whether closely integrated or decoupled, this combination can be a potent tool for modern web application development.