quickjs-emscripten
AnswerOverflow
quickjs-emscripten | AnswerOverflow | |
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21 | 25 | |
1,130 | 752 | |
- | 2.4% | |
9.4 | 9.6 | |
20 days ago | 4 days ago | |
TypeScript | TypeScript | |
GNU General Public License v3.0 or later | GNU General Public License v3.0 or later |
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
quickjs-emscripten
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New QuickJS Release
Based on your comment below I think you figured out the difference - but if you're looking to execute JS, you can pick between ShadowRealm (where available, or using a polyfill) or my library quickjs-emscripten.
Pros of quickjs-emscripten over ShadowRealm:
- You can use quickjs today in any browser with WASM. ShadowRealm isn't available yet, and polyfills have had security issues in the past. See https://www.figma.com/blog/an-update-on-plugin-security/
- In ShadowRealm eval, untrusted code can consume arbitrary CPU cycles. With QuickJS, you can control the CPU time used during an `eval` using an [interrupt handler] that's called periodically during the eval.
- In ShadowRealm eval, untrusted code can allocate arbitrary amounts of memory. With QuickJS, you can control both the [stack size] and the [heap size] available inside the runtime.
- quickjs-emscripten can do interesting things with custom module loaders and facades that allow synchronous code inside the runtime to call async code on the host.
Pros of ShadowRealm over QuickJS:
- ShadowRealm will (presumably?) execute code using your native runtime, probably v8, JavaScriptCore, or SpiderMonkey. Quickjs is orders of magnitude slower than JIT'd javascript performance of v8 etc. It's also slower than v8/JSC's interpreters, although not by a huge amount. See [benchmarks] from 2019.
- You can easily call and pass values to ShadowRealm imported functions. Talking to quickjs-emscripten guest code requires a lot of fiddly and manual object building.
- Overall the quickjs(-emscripten) API is verbose, and requires 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...
[heap size]: https://github.com/justjake/quickjs-emscripten/blob/main/doc...
[benchmarks]: https://bellard.org/quickjs/bench.html
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Extism Makes WebAssembly Easy
The thing I want to achieve with WebAssembly is still proving a lot harder than I had anticipated.
I want to be able to take strings of untrusted code provided by users and execute them in a safe sandbox.
I have all sorts of things I want this for - think custom templates for a web application, custom workflow automation scripts (Zapier-style), running transformations against JSON data.
When you're dealing with untrusted code you need a really robust sandbox. WebAssembly really should be that sandbox.
I'd like to support Python, JavaScript and maybe other languages too. I want to take a user-provided string of code in one of those languages and execute that in a sandbox with a strict limit on both memory usage and time taken (so I can't be crashed by a "while True" loop). If memory or time limit are exceeded, I want to get an exception which I can catch and return an error message to the user.
I've been exploring options for this for quite a while now. The furthest I've got was running Pyodide inside of Deno: https://til.simonwillison.net/deno/pyodide-sandbox
Surprisingly 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.
Can Extism help with this? I'm confident I'm not the only person who's looking for a solution here!
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Node on Web. Use Nodejs freely in your browser with Linux infrastructure.
"Safely execute untrusted Javascript in your Javascript, and execute synchronous code that uses async functions" quickjs-emscripten, NPM
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Sandboxing JavaScript Code
This maybe, as a start?
https://github.com/justjake/quickjs-emscripten
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Hacker News top posts: Nov 20, 2022
QuickJS Running in WebAssembly\ (17 comments)
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QuickJS Running in WebAssembly
The library was inspired by Figma’s blog posts about their plug-in system: https://github.com/justjake/quickjs-emscripten#background
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Show HN: Run unsafe user generated JavaScript in the browser
If you need to call into user-generated Javascript synchronously or have greater 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 runtime, but possibly faster than async calls using postMessage. As an added bonus, it can make async functions in the host appear to be synchronous inside the sandbox using asyncify: https://emscripten.org/docs/porting/asyncify.html.
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Why Would Anyone Need JavaScript Generator Functions?
You can use One Weird Trick with generator functions to make your code "generic" over synchronicity. I use this technique to avoid needing to implement both sync and async versions of some functions in my quickjs-emscripten library.
The great part about this technique as a library author is that unlike choosing to use a Promise return type, this technique is invisible in my public API. I can write a function like `export function coolAlgorithm(getData: (request: I) => O | Promise): R | Promise`, and we get automatic performance improvement if the user's function happens to return synchronously, without mystery generator stuff 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...
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Why Am I Excited About WebAssembly?
This seems like a pretty nice, recently enabled way of getting a sandboxed js environment: QuickJS compiled to WASM: https://github.com/justjake/quickjs-emscripten.
AnswerOverflow
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I Live in IRC (2015)
> TOO many bots log entire channels out to public html sites. This is prevalent in everything like discord etc but the degree to it in IRC is just ridiculous god knows what any of those 1500 bots in a channel are doing.
These sorts of bots are quite rare on Discord, you usually have to make an account to be able to see anything. There have been attempts at standardizing this (like https://www.answeroverflow.com/) but they haven't taken off. Public logs are much more common on IRC than on Discord.
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Posthog is closing their Slack community in favor of forum
Related: AnswerOverflow makes Discord messages searchable on Google/ other search engines. It’s open source.
https://www.answeroverflow.com/
- The Internet Is Full of AI Dogshit
- Extism Makes WebAssembly Easy
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Don't Use Discord as a Forum
I agree that the discord centralization for Q&A is becoming problematic, it makes it less discoverable and searchable (Had this problem a lot with Svelte).
That said, I have had success so far using https://www.answeroverflow.com/ to search discord for questions. It sucks we have to use such tools, but given the current situation, it's also better to adapt.
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Discord Is Not Documentation
We've started mirroring our Discord to the web using https://www.answeroverflow.com/
You could roll your own equivalent but AnswerFlow has some nice features and handles issues around consent nicely.
If you're starting a Discord then I'd strongly recommend stating upfront that you might mirror content to another location even if you're not doing it now - it makes it a lot easier than doing so further down the line.
A better solution would be to not use Discord but friction, push-back from my colleagues on alternatives and a fear of fragmenting the community made this the best option for us.
- Show HN: Answer Overflow – Indexing Discord content into the web
- Show HN: Indexing Discord content into the web Answer Overflow
- Sobre o fechamento do sub
What are some alternatives?
wasmtime - A fast and secure runtime for WebAssembly
DFeed - D news aggregator, newsgroup client, web newsreader and IRC bot
wasmer - 🚀 The leading Wasm Runtime supporting WASIX, WASI and Emscripten
linen.dev - Lightweight Google-searchable Slack alternative for Communities
wizer - The WebAssembly Pre-Initializer
t3-stripe - Example Stripe integration with create-t3-app bootstrapped Next.js application
rr - Record and Replay Framework
DiscordChatExporter-frontend - Browse json files exported by Tyrrrz/DiscordChatExporter in familiar discord like user interface
go - The Go programming language
DiscordChatExporter - Exports Discord chat logs to a file
iPlug2 - C++ Audio Plug-in Framework for desktop, mobile and web
multihash-serialise - Haskell libraries for interacting with IPFS