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Show HN: Nova JavaScript Engine

(github.com)
269 points aapoalas | 2 comments | 17 Nov 24 23:07 UTC | HN request time: 0.416s | source

We're building a different kind of JavaScript engine, based on data-oriented design and willingness to try something quite out of left field. This is most concretely visible in our major architectural choices:

1. All data allocated on the JavaScript heap is placed into a type-specific vector. Numbers go into the numbers vector, strings into the strings vector, and so on.

2. All heap references are type-discriminated indexes: A heap number is identified by its discriminant value and the index to which it points to in the numbers vector.

3. Objects are also split up into object kind -specific vectors. Ordinary objects go into one vector, Arrays go into another, DataViews into yet another, and so on.

4. Unordinary objects' heap data does not contain ordinary object data but instead they contain an optional index to the ordinary objects vector.

5. Objects are aggressively split into parts to avoid common use-cases having to reading parts that are known to be unused.

If this sounds interesting, I've written a few blog posts on the internals of Nova over in our blog, you can jump into that here: https://trynova.dev/blog/what-is-the-nova-javascript-engine

1. gardaani ◴[18 Nov 24 11:39 UTC] No.42171562[source]▶
Is this an experimental only JS engine or do you aim to implement the entire ECMAscript specification?

I have been following the Rust Boa project, but I think that it isn't production ready, yet. https://github.com/boa-dev/boa

replies(1): >>42171608 #
2. aapoalas ◴[18 Nov 24 11:48 UTC] No.42171608[source]▶
The aim is absolutely to implement the entire ECMAScript specification. Progress has slowed down recently, as I've been both busy with other things and tied up in making the engine work with interleaved GC.

A secondary aim is to have a bunch of feature flags that allows the engine to drop out support for specification parts that a particular embedder doesn't care about. That obviously fights with the "implement the entire ECMAScript specification" goal, but I just hate indexed property getters and setters with a passion and want to see them gone wherever I go.

Boa is a great project and I believe it is being used in some production systems. I've met and exchanged some ideas with the main developer, Jason Williams, and even received the greatest praise that I could imagine: Boa will (or did?) take some inspiration from Nova on its GC refactoring. Nova has also copied (with proper attribution of course) a few minor parts from Boa, like whitespace skipping code for some spec abstract operations.

I highly recommend keeping an eye out and using Boa if you have the chance.