Hermes JavaScript Engine for React Native
Article Summary
Facebook just open-sourced Hermes, a JavaScript engine built specifically for React Native on Android. This isn't just another optimization tweak. It's a ground-up rethink of how JS should run on mobile.
At Chain React, Facebook announced Hermes, a lightweight JavaScript engine designed for the constraints of mobile devices. After analyzing performance data, they realized the JS engine itself was the bottleneck for startup performance and app size, especially on mass-market Android devices with limited resources.
Key Takeaways
- Hermes reduces memory usage, download size, and time to interactive (TTI)
- Built specifically for constrained mobile environments with limited memory and slow storage
- Already available for existing React Native apps with simple integration guide
- Targets mass-market Android devices, not just flagship phones
Critical Insight
Hermes tackles React Native's biggest mobile performance bottlenecks by replacing the JavaScript engine with one purpose-built for resource-constrained devices.
