mastodon 4.8.0-nightly.2026-10-06An Open Source, embeddable engine for JavaScript and WebAssembly. Maintained by the SpiderMonkey team at @mozilla@mastodon.social.
Read about the latest SpiderMonkey changes here: https://spidermonkey.dev/blog/
Learn about the engine: https://spidermonkey.dev/docs/
Browse the code: https://searchfox.org/mozilla-central/source/js/src
Check out our online demo of SpiderMonkey compiled to WebAssembly! https://mozilla-spidermonkey.github.io/sm-wasi-demo/
Exciting news: we're shipping Temporal in Firefox 139! Temporal is a new API for working with dates and times in JS.
This is a very large feature and our implementation was contributed by a single volunteer.
Read about it in our blog post: https://spidermonkey.dev/blog/2025/04/11/shipping-temporal.html
It's already available in @firefoxnightly@mastodon.social behind the `javascript.options.experimental.temporal` pref in about:config.
MDN blog post about Temporal: https://developer.mozilla.org/en-US/blog/javascript-temporal-is-coming/
Temporal is now enabled by default in @firefoxnightly@mastodon.social!
We are a little late to the party. How about we do an #introduction?
Hi Fediverse, we are SpiderMonkey, @mozilla@mastodon.social’s #opensource engine for #JavaScript and #WebAssembly.
SpiderMonkey is used in Firefox, Servo and various other projects.
This account is run by our engineers, and none of us know how social media works. We were told to use hashtags.
#firefox #opensource #compilers #wasm #foss #privacy #security #performance #community
Nice to meet you!
It's time for another newsletter!
We're making good progress on performance and are also implementing several new features such as Temporal. Read about it here: https://spidermonkey.dev/blog/2023/08/07/newsletter-firefox-116-117.html
#firefox #opensource #mozilla #wasm #javascript #performance #foss #newsletter
SpiderMonkey News! In this upcoming firefox release (111) we've landed work in the following areas:
* Improving Performance
* Adding Module Support to Workers (behind a flag on nightly, please test it and report bugs!)
* WASM GC
* Introducing more robust caching
We've also had an excellent contribution from PLCT lab, ISCAS introducing a RISC-V backend for our JIT.
Read about it in detail in our news letter: https://spidermonkey.dev/blog/2023/02/16/newsletter-firefox-110-111.html
Late last year, we implemented the Import Maps specification in Firefox. Yoshi (the engineer working on it) wrote an in-depth introduction to it, along with a deep dive that you can expect next week!
Read the blog post here: https://spidermonkey.dev/blog/2023/02/23/javascript-import-maps-part-1-introduction.html
Check out our latest two news letters!
In April we wrote about the headway we made on Performance and WASM GC: https://spidermonkey.dev/blog/2023/04/14/newsletter-firefox-112-113.html
In June, we continued this work, as well as shipping worker modules! https://spidermonkey.dev/blog/2023/06/09/newsletter-firefox-114-115.html
#opensource #javascript #firefox #wasm #foss #compilers #performance
Last week we introduced what import maps are and how they work. This week Yoshi explores the feature in depth, in the second part of his two part series on Import maps.
Read the blog post here: https://spidermonkey.dev/blog/2023/03/02/javascript-import-maps-part-2-in-depth-exploration.html
I found the keys! Check out our October Newsletter, we will have more for you this month :) https://spidermonkey.dev/blog/2022/10/24/newsletter-firefox-106-107.html