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justjake/quickjs-emscripten

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Safely execute untrusted Javascript in your Javascript, and execute synchronous code that uses async functions

28 mentions on Hacker News by 10 people: 2 stories, 26 comments · first 2020-01-14 · latest 2026-02-14

Mentions per year 28 mentions · busiest year 2022 (11)
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  1. …at embedding but nowhere close to luajit in terms of speed. (i have some experience with quickjs https://github.com/justjake/quickjs-emscripten ) as an aside i’m curious how quickjs/mquickjs compares to mruby in speed and size. something…
    comment by jitl · 2026-02-14 · in Vim 9.2
  2. …own. Someone took QuickJS and put it in wasm so you can run QuickJS in the browser or in node. https://github.com/justjake/quickjs-emscripten Fabrice Bellard is on another planet when it comes to programming. He also wrote FFmpeg and QEMU…
    comment by hackthemack · 2025-10-11 · in Building a JavaScript Runtime using C
  3. …will use Symbol.for('Symbol.dispose'), but other compilers may choose a different symbol... https://github.com/justjake/quickjs-emscripten/blob/aa48b619...
    comment by jitl · 2025-05-17 · in JavaScript's New Superpower: Explicit Resource Management
  4. …based sandboxing. I’m referring to running quickjs in wasm by compiling it with emscripten. https://github.com/justjake/quickjs-emscripten
    comment by feznyng · 2024-12-27 · in Lua is so underrated
  5. …modules or let them submit JS that will be run in a JS interpreter running in WebAssembly. I think https://github.com/justjake/quickjs-emscripten or https://github.com/fermyon/StarlingMonkey (used by https://github.com/bytecodealliance/Comp…
    comment by AgentME · 2024-12-18 · in The XOR Texture (2004)
  6. …the browser (specifically tested with ESM.sh), as well as Cloudflare Workers, NodeJS, Deno: https://github.com/justjake/quickjs-emscripten?tab=readme-ov... It has APIs for exposing host functions, calling guest functions, custom module…
    comment by jitl · 2024-07-07 · in Show HN: Execute JavaScript in a WebAssembly QuickJS sandbox
  7. …- https://www.figma.com/blog/an-update-on-plugin-security/ Quickjs-emscripten README: https://github.com/justjake/quickjs-emscripten
    comment by jitl · 2024-07-07 · in Show HN: Execute JavaScript in a WebAssembly QuickJS sandbox
  8. …manual memory management of references to values inside the quickjs runtime. [interrupt handler]: https://github.com/justjake/quickjs-emscripten/blob/main/doc... [stack size]: https://github.com/justjake/quickjs-emscripten/blob/main/doc...…
    comment by jitl · 2023-12-09 · in New QuickJS Release
  9. …CPU time and memory use, a custom module system, or call async code synchronously, check it out: https://github.com/justjake/quickjs-emscripten It's used by a few projects like Hoppscotch, a Postman-like visual API client (…
    comment by jitl · 2023-12-09 · in New QuickJS Release
  10. …I've not found a good pattern for running a JavaScript interpreter in a WASM sandbox yet. https://github.com/justjake/quickjs-emscripten looks promising but I've not found the right recipe to call it from server-side Python or Deno yet.…
    comment by simonw · 2023-10-04 · in Extism makes WebAssembly easy
  11. This maybe, as a start? https://github.com/justjake/quickjs-emscripten See https://github.com/justjake/quickjs-emscripten/blob/main/c/i... for the mem/CPU limits.
    comment by tyingq · 2023-04-20 · in Sandboxing JavaScript Code
  12. The library was inspired by Figma’s blog posts about their plug-in system: https://github.com/justjake/quickjs-emscripten#background
    comment by jitl · 2022-11-20 · in QuickJS Running in WebAssembly
  13. ▲ 93
    QuickJS Running in WebAssembly
    story by angrygoat · 2022-11-20 · 26 comments
  14. …control over the sandbox environment, you can use WebAssembly to run a Javascript interpreter: https://github.com/justjake/quickjs-emscripten#quickjs-emscr... QuickJS in WebAssembly is much slower than your browser's native Javascript…
    comment by jitl · 2022-11-19 · in Show HN: Run unsafe user generated JavaScript in the browser
  15. …showing up in the function signature. Helper to make a function that can be either sync or async: https://github.com/justjake/quickjs-emscripten/blob/ff211447... Uses: https://cs.github.com/justjake/quickjs-emscripten?q=yield*+l...
    comment by jitl · 2022-11-07 · in Why would anyone need JavaScript generator functions?
  16. QuickJS compiled to WASM seems like a pretty nice way of getting a sandboxed js environment: https://github.com/justjake/quickjs-emscripten . Curious if people have seen any other routes to doing it via WASM.
    comment by westoncb · 2022-07-17 · in Why am I excited about WebAssembly?
  17. …JS interpreter with more modern language support, from NodeJS or the web called QuickJS-Emscripten: https://github.com/justjake/quickjs-emscripten This was inspired by seeing Duktape WASM build on HN (…
    comment by jitl · 2022-07-03 · in Duktape is an embeddable JavaScript engine
  18. …with custom <script> elements. I have a solution to plugin CPU blocking for pure API plugins ( https://github.com/justjake/quickjs-emscripten ) but not a way to meld it safely with HTML access.
    comment by jitl · 2022-04-10 · in Ask HN: What Happened to Evernote?
  19. …I want to offer a ton of different build variants of my core WASM file. Here’s what I tried: https://github.com/justjake/quickjs-emscripten/blob/master/t... This approach works great for NodeJS, but once I ran a test bundle I found that…
    comment by jitl · 2022-03-28 · in Recommendations when publishing a WASM library
  20. …JavaScript ecosystem projects that do actually need to build things with interdependency (eg https://github.com/justjake/quickjs-emscripten/blob/master/M... ). I’ve also seen Makefiles grown to be horrendous monstrosities masquerading as…
    comment by jitl · 2022-03-14 · in Why I Prefer Makefiles over Package.json Scripts
  21. …code, building plugin systems, etc, I have a library here that wraps a WASM build of QuickJS: https://github.com/justjake/quickjs-emscripten#quickjs-emscr... I believe Figma uses QuickJS for their plugin system.
    comment by jitl · 2022-03-08 · in QuickJS JavaScript Engine
  22. …a basic interface to create VMs, expose APIs from the host to the guest, and evaluate code. Repo: https://github.com/justjake/quickjs-emscripten NPM: https://www.npmjs.com/package/quickjs-emscripten Areas of work: - Make the library…
    comment by jitl · 2022-02-01 · in Ask HN: Who wants to collaborate?
  23. …WASM. I know of a company using my library to implement "plugin"/user-scripting using my library. https://github.com/justjake/quickjs-emscripten#quickjs-emscr...
    comment by jitl · 2021-06-02 · in Making JavaScript run fast on WebAssembly
  24. …igma.com/blog/how-we-built-the-figma-plugin-sys... [1] - https://bellard.org/quickjs/bench.html [2] - https://github.com/justjake/quickjs-emscripten [3] - https://github.com/lowdefy/lowdefy/blob/main/packages/operat...
    comment by gervwyk · 2021-05-06 · in SpiderMonkey JavaScript/WebAssembly Engine
  25. …https://github.com/tc39/proposal-realms/#ecmascript-spec-pro... https://github.com/tc39/proposal-ses https://github.com/justjake/quickjs-emscripten
    comment by tonyhb · 2021-01-26 · in Evaluating JavaScript in the browser for a low code product
  26. …wrapping QuickJS if you don’t want to do the emscripten build or figure out the C API yourself: https://github.com/justjake/quickjs-emscripten
    comment by jitl · 2020-10-25 · in A small but complete JavaScript engine
  27. …implement untrusted JavaScript evaluation in your own (JavaScript) software, check out my library: https://github.com/justjake/quickjs-emscripten
    comment by jitl · 2020-09-29 · in Show HN: Elsa – A QuickJS wrapper written in Go
  28. ▲ 3
    Show HN: JS bindings for QuickJS, control over eval, inspired by Figma's plugins
    story by jitl · 2020-01-14 · 0 comments