Not named after the French couturier but the Greek god of trade, roads, and thieves

Facebook on Thursday released a JavaScript engine called Hermes under an open source MIT license to improve the performance of React Native apps.

The ad biz made the announcement at the Chain React 2019 conference, which focuses on React Native development.

It's supposed advantage is that developers can target all three mobile platforms with a single code base; but as with any cross-platform framework, there are trade offs in terms of performance, security and flexibility.

Hermes aims to address the performance trade-off, which is particularly acute for Facebook because it has complicated JavaScript-dependent mobile apps.

As Google engineering manager Addy Osmani has observed, Google's V8 JavaScript engine spends a lot of time parsing and compiling JavaScript code before running it, leading to slow mobile application startup times.

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