---
title: "Saying goodbye to asm.js"
url: https://daily.dev/posts/saying-goodbye-to-asm-js-dkewl884t
source_url: https://spidermonkey.dev/blog/2026/05/20/saying-goodbye-to-asmjs.html
type: article
source: "SpiderMonkey"
published: 2026-05-20T12:09:14.933Z
updated: 2026-05-20T12:09:34.188Z
tags: ["javascript", "webassembly", "firefox"]
reading_time: 3
upvotes: 68
comments: 6
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Saying goodbye to asm.js

**[SpiderMonkey](https://daily.dev/sources/spidermonkey)** · 3 min read · 68 upvotes · 6 comments

## Summary

Firefox 148 disables SpiderMonkey's asm.js optimizations by default, with full removal planned for a future release. asm.js, Mozilla's 2013 technology for running C/C++ code at near-native speed on the web, paved the way for WebAssembly. Since WebAssembly has now fully succeeded and asm.js usage has largely migrated, maintaining the separate asm.js path only adds maintenance burden and attack surface. Existing asm.js code continues to run via the regular JIT without breaking, but recompiling to WebAssembly is recommended for better performance and smaller binaries. The asm.js compiler OdinMonkey is being retired after 13 years, succeeded by the WebAssembly compilers BaldrMonkey and RabaldrMonkey.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://spidermonkey.dev/blog/2026/05/20/saying-goodbye-to-asmjs.html>

## Community discussion

Top comments from developers on daily.dev.

**@garrylowther63** · 2 upvotes

> > "WebAssembly has now fully succeeded"
> Is this a joke?

**@lauramoss** · 2 upvotes

> End of an era for asm.js — crazy how much it helped shape the modern web tooling we take for granted now.

**@byteoutlaw** · 0 upvotes

> Serious predecessor! - Helped change the web forever, imagine how many polyfills have pawed the web for todays browsers.

## Similar posts on daily.dev

- [Firefox in WebAssembly](https://daily.dev/posts/firefox-in-webassembly-lwf41zu6v) · Hacker News · 1 upvotes · 0 comments

---

Tags: [#javascript](https://daily.dev/tags/javascript), [#webassembly](https://daily.dev/tags/webassembly), [#firefox](https://daily.dev/tags/firefox)

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