# Espruino JavaScript Interpreter
**URL:** https://f.ruuvi.com/t/espruino-javascript-interpreter/455
**Category:** 🇬🇧 RuuviLab (article comments)
**Created:** [29 June 2017 09:38 UTC](https://f.ruuvi.com/t/espruino-javascript-interpreter/455 "2017-06-29T09:38:07Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@lauri](https://f.ruuvi.com/u/lauri)
#### Post date: [29 June 2017 09:38 UTC](https://f.ruuvi.com/t/espruino-javascript-interpreter/455/1 "2017-06-29T09:38:08Z")
This topic is dedicated to comments and conversations about the following RuuviLab tutorial:
> **[RuuviLab - Espruino JavaScript Interpreter](https://lab.ruuvi.com/espruino/)**
>
> Program RuuviTag in JavaScript
If you don’t see any comments yet, don’t be afraid to be the first one to contribute!
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### Author:  [@Alexander\_Enlund](https://f.ruuvi.com/u/Alexander_Enlund)
#### Post date: [4 February 2019 17:54 UTC](https://f.ruuvi.com/t/espruino-javascript-interpreter/455/2 "2019-02-04T17:54:54Z")
Hello.
I’m wondering how long the battery lifetime is when using Espruino Interpreter on a RuuviTag and also how much memory does Espruino take?
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### Author:  [@otso](https://f.ruuvi.com/u/otso)
#### Post date: [7 February 2019 08:49 UTC](https://f.ruuvi.com/t/espruino-javascript-interpreter/455/3 "2019-02-07T08:49:21Z")
Answer to both is “it depends”.
I’m not sure about exact flash or RAM requirement of Espruino, but according to [https://www.espruino.com/Performance](https://www.espruino.com/Performance) Espruino fits in under 8 kB of RAM while RuuviTag has 64 kB of RAM - whatever is configured for the Softdevice.
It’s possible to code very power efficient programs with Espruino, but there are some gotchas. For example delay keeps CPU active and therefore consumes power.