• Command line flag --experimental-default-type=module: It changes the default module type from CommonJS to ESM if a file or an input has no explicit type.

  End goal: “We are also exploring using detection of ES module syntax as a way of Node.js knowing when to interpret files as ES modules. Our goal is to eventually find a way to support ES module syntax by default with minimal breaking changes.”

• Stable WebStreams and fetch().

• Client-side WebSocket API

• Support for globs in the Node.js test runner

• “In Node.js 21, we've introduced the global navigator object, enhancing web interoperability. Now, developers can access hardware concurrency information through navigator.hardwareConcurrency.”

• V8 11.8 with Array grouping, ArrayBuffer.prototype.transfer and more

• Various performance improvements

[Quoting the slides:]

JWST is a static compiler developed by Huawei Tech. & Beihang University for compiling JavaScript to Wasm and native code:

• Uses QuickJS bytecode as input, and outputs LLVM IR.
• Has the same pass rate as QuickJS for Ecma Test262.
• Caveats (via a blog post by Thomas Steiner):
  • The compiled Wasm is large and not always faster.
  • The compiler may never be open-sourced.