js-compute-runtime VS engine262

There are multiple JavaScript runtimes. SpiderMonkey is one example that has nothing to do with Node.js, see (js-compute-runtime)[https://github.com/fastly/js-compute-runtime].

We listened to the community feedback, filled in feature gaps, and addressed many bugs in the SDK. Not only that, we’ve also overhauled the SDK reference docs making it easier for you to know what’s supported and how to implement the features. All the Fastly specific features of the JS SDK now have interactive example applications in the documentation.

These are good questions! Here's some answers from the corner of the world I know best as a Wasmtime contributor at Fastly:

1. Spidermonkey.wasm is the basis of Fastly's JavaScript on Compute@Edge support. We have found it to be faster than QuickJS. The source code is here: https://github.com/fastly/js-compute-runtime.

2. Fastly Compute@Edge is built on wasmtime. You can develop web services for it in Rust, JS, and Go: https://developer.fastly.com/learning/compute/

3. Fastly's multi-tenant platform is closed source, but our single-tenant local development platform, which also uses wasmtime under the hood as well, is open source: https://github.com/fastly/viceroy. It isn't a big leap to make viceroy multi-tenant: Wasmtime provides everything you need, and all Viceroy would have to do is dispatch on e.g. HTTP host header to the correct tenant. Our multi-tenant platform is closed source because it is very specialized for use on Fastly's edge, not because the multi-tenant aspect is special.

btw. for what it's worth their javascript to wasm is opensource:

- https://github.com/fastly/js-compute-runtime

- https://github.com/tschneidereit/spidermonkey-wasi-embedding

and besides that it is slower than nodejs it is still plenty fast (no matter that it is not as fast as they want) btw. it's startup is faster than node. (maybe better pgo might help)

engine262

Indeed. ECMA-262 has been implemented using JavaScript https://github.com/engine262/engine262.

Node.js is not the only JavaScript runtime. JavaScript runtimes have been written using JavaScript alone, see engine262. There is also Deno, QuickJS, txiki.js, Bun, none of which use COmmonJS by default, SpiderMonkey, et al.

for an interpreted language like JS, this project is really nice https://github.com/engine262/engine262. More or less 2 parts: parser and evaluator

That is a bit complex, so here's a list of JS engines: if you pick one written *in* JS, that would probably be most useful -- engine262 for example

then you might be impressed by https://github.com/engine262/engine262 as well

Engine 262

It's outside of what you asked for, but here's a JavaScript engine in JavaScript. Might make for some interesting bedtime reading!

Interesting to see a JS implementation written in JS:

https://github.com/engine262/engine262/

(The readme explains what the point of it is.)