Switch from V8 to JavaScriptCore?

[taoeffect]

Bun is apparently significantly faster than Deno and Node.js, and the performance seems to be attributed to WebKit's JavaScriptCore engine.

Would Deno consider swtiching its JS engine to JavaScriptCore? How difficult would it be?

[BlackAsLight]

What makes you say its attributed to WebKit? Bun has a tendency to offer a lot of non-native APIs that push a lot of the computational calculations outside of the JavaScript context. Doing that does allow you to get insane performance compared to the equivalent JavaScript code. This doesn't seem to be the direction Deno wants to head in as they want people making libraries in JavaScript to offer these features compared to implementing everything themselves.

The Web APIs for Uint8Array.toBase64 and Uint8Array.fromBase64 are examples of the type of performance gain you can get when you move the computational calculations outside of the JavaScript context. The best JavaScript and WASM versions of a Base64 encoder are noticeably slower than native APIs.

Additionally, moving to WebKit would require an insane amount of effort. Since Deno is written in Rust, a lot of effort has already been put in to create rust bindings from the v8 engine. They'd essentially have to start all over again to create bindings for WebKit.

Lastly, there are many Web APIs that WebKit is lagging behind in compared to v8 and Apple at this time don't seem interested in dedicating time to implementing them. There are sections of https://jsr.io/@std that break under WebKit due to them not implementing the APIs everyone else has implemented.

[taoeffect]

What makes you say its attributed to WebKit?

You're right to question that, it's just a guess. Both Bun and Deno are written in highly-performant languages, so it's really an assumption that it's the JS engine that accounts for the performance differences.

And it's also possible that the benchmarks that Bun advertises are misleading (perhaps Deno performs better on other benchmarks).

There are sections of https://jsr.io/@std that break under WebKit due to them not implementing the APIs everyone else has implemented.

Hmm, well that would definitely be concerning. Feel free to close this issue if it's not something the team considers viable, or consider it as a general performance related issue.