Babel vs Hermes: What are the differences?

Introduction

Babel and Hermes are both tools used in the development of JavaScript applications. While Babel is a widely-used JavaScript compiler, Hermes is a JavaScript engine specifically designed for mobile platforms. Understanding the key differences between these two tools is essential for developers to make informed decisions regarding their JavaScript projects.

1. Performance: One significant difference between Babel and Hermes lies in their performance. Babel is primarily used to compile and transform JavaScript code, allowing developers to use modern JavaScript features that are not natively supported by all browsers. On the other hand, Hermes focuses on optimizing the runtime performance of JavaScript code, particularly for mobile applications. It achieves this by leveraging ahead-of-time (AOT) compilation, resulting in faster startup times and lower memory consumption compared to Babel.

2. Mobile Platform Compatibility: Hermes is specifically designed for mobile platforms, particularly Android applications built using React Native. It is highly optimized to provide a better user experience on mobile devices, offering features like improved battery efficiency and reduced memory footprint. Babel, on the other hand, is not platform-specific and can be used across different environments, including web browsers and Node.js.

3. Bundle Size: When it comes to the size of the output bundle, Babel tends to produce larger bundle sizes due to its capability to transform and compile modern JavaScript code. This can potentially impact the loading time of web applications, especially for users with slower network connections. On the contrary, Hermes is optimized to generate smaller bundle sizes since it performs AOT compilation, resulting in faster application loading times on mobile devices.

4. Development Workflow: Babel is widely used in the JavaScript community and integrates seamlessly into popular tools like webpack and Babel CLI. It allows developers to utilize cutting-edge JavaScript features while maintaining compatibility with older browsers and environments. Hermes, on the other hand, has a more specific use case and is primarily integrated with React Native for Android. It may require additional configurations and adjustments to work within existing JavaScript development workflows.

5. Supported Language Features: Babel has extensive support for the latest JavaScript language features, allowing developers to write code using modern syntax and features. It provides backward compatibility with older JavaScript versions, enabling a wider range of target environments. Hermes, being a JavaScript engine dedicated to mobile platforms, focuses on providing efficient execution of JavaScript without the need for additional compatibility layers. This may result in limited support for certain language features, as it prioritizes performance optimization over language feature support.

6. Debugging Capability: Babel, being a compiler, does not impact the debugging capabilities of JavaScript. Developers can still use standard debugging tools provided by browsers and other JavaScript environments. In contrast, Hermes incorporates its own debugging techniques and tools specifically built for mobile platforms, offering enhanced debugging capabilities tailored for Android applications developed using React Native.

In Summary, Babel is a widely-used JavaScript compiler that provides extensive language feature support and compatibility across different environments, while Hermes is a JavaScript engine designed for mobile platforms, focusing on performance optimization, smaller bundle sizes, and enhanced debugging capabilities specifically for Android applications built using React Native.