[aapoalas]

Hey, thank you for the question!

We owe a lot to Boa: I would like to call Jason Williams a personal acquaintance, we've discussed JS engines in general, and Boa and Nova in particular both face to face and online. Some parts of builtin methods, like float parsing, have been copied verbatim from Boa with copyright notices to Jason.

As for comparisons, the focal difference is perhaps the starting aims of each project: Boa was started by Jason (according to his Node.JS conf talk) to see if one can build a JS engine in Rust, and what building a JS engine means anyhow. They've since showed that indeed this can be done, no problem whatsoever. Because Boa walked, Nova could "run": I started working on Nova actively because I wanted to see what building a JS engine using an ECS-like architecture and data-oriented design would look like; what would it mean to get rid of the traditional structural inheritance / object-oriented design paradigm of JS engines, and what would the resulting engine look like?

So, Boa is a quest to show that a (traditional) JS engine can be built in Rust. Nova is a quest to show that Rust-like non-traditional architectures can be applied to a JS engine, and hoping that this will lead to unforeseen (or previously unappreciated) benefits.