I guess technically Node, but in practice JS, since Node is still the de facto standard non-browser JS runtime. "Just use X" where X is some other build tool/runtime/testing ecosystem is another weird trope that's somehow considered acceptable advice in JS, but would be a massive undertaking for any non-trivial project.
Maybe if someone suggests Deno or similar, but Bun is a drop in for Node and is as such completely interoperable with your Node code. Its similar to how you can adopt PNPM easily because it’s a drop in for NPM, where as yarn and others are their own things.
