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Comment by snarfy | Hacker News Reader

One of the reasons I brought this up was a recent article about energy efficiency of programming languages.[1] JavaScript is ~2x less energy efficient than Java, so it will eat twice the battery.

[1] https://sites.google.com/view/energy-efficiency-languages/re...

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"so it will eat twice the battery" may be nearly true on headless boxes running CPU heavy workloads. Mobile apps are about as far from that as you can possibly get. Sure it's probably a measurable impact, but I would expect it's less of an impact than things like how bright the backlighting is, whether you keep GPS usage to a minimum, how well you minimize and batch network communication, etc, etc. CPU is a small part of a phone's power budget and mobile apps spend a lot of time with the cpu largely idle.

> JavaScript is ~2x less energy efficient than Java, so it will eat twice the battery.

While the citation you provide is interesting, it doesn't inherently prove that in real-world usage, React Native apps consume twice the power of their native counterparts.

Wow, that's a great analysis. In addition to being less efficient, there's definitely more overhead with the extra layer of JS underneath. Just of the top of my head, this might be a bigger issue with apps that constantly refresh the screen or have real-time interactions (e.g. games or Slack), and not so much apps that are essentially a series of forms (code only runs when you interact). With our app, what affects battery usage most is the location analysis that happens in the background. It's one of the areas the development team spends a lot of time testing and optimizing.

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