Capybara vs Nightwatchjs: What are the differences?

Capybara and Nightwatchjs are both popular testing frameworks used for automated testing of web applications. However, they have key differences that set them apart.

1. **Testing Approach**: Capybara is primarily used for feature testing in Ruby on Rails applications, focusing on simulating user interactions with the application through a web browser. On the other hand, Nightwatchjs is a framework for end-to-end testing of web applications that uses Selenium WebDriver and can test multiple browsers and operating systems simultaneously.
   
2. **Language Support**: Capybara is built for Ruby and works best with Ruby web applications, while Nightwatchjs is written in JavaScript and can be used for testing applications built with any language as long as it can be interacted with through a web browser.

3. **Implementation**: Capybara interacts with web applications using Rack applications or actual server requests in Ruby, whereas Nightwatchjs communicates with the web application through Selenium and WebDriver protocols, enabling cross-browser testing.

4. **Asynchronous Support**: Capybara handles asynchronous testing automatically using timeouts and waiting for specific elements to appear before proceeding with test execution. In contrast, Nightwatchjs provides explicit handling of asynchronous operations using built-in methods like `executeAsync` and `waitForElement`.

5. **Community and Ecosystem**: Capybara has been around longer, making it have a more robust community and ecosystem with a wide range of plugins and extensions available. Nightwatchjs, while growing in popularity, might have a smaller but equally supportive community.

In Summary, Capybara focuses on feature testing in Ruby web applications, while Nightwatchjs is more versatile with multi-browser testing capabilities using Selenium WebDriver.