Generating TypeScript with TypeScript

DevOps.js

DevOps.js Conf 2024

Brendan Coll

Testing Alternative Runtimes with Node and Vitest

Node Congress

Node Congress 2024

Running Java in Node.js with WebAssembly

Node Congress 2025

Many organisations have a lot of Java code. As they adopt newer technologies such as Node.js or Cloudflare Workers, maintaining interoperability with this existing code is important. WebAssembly is an instruction set for a stack-based virtual machine. This is the same type of abstract machine the Java Virtual Machine (JVM) uses making it possible to convert existing Java code to WebAssembly. This would allow Java code to be "imported" directly without rewrites, meaning it could be executed anywhere WebAssembly was supported. In this talk, I'll describe a research project that does just that. I’ll speak about the history of WebAssembly, what Java bytecode looks like, how to interpret it, decompilation techniques and implementing polymorphic objects.

A deep dive into how we built support for running Vitest tests in the Cloudflare Workers runtime. We'll start by giving an overview of the Cloudflare developer platform, including our open-source workerd JavaScript runtime and local simulator Miniflare. Next we'll talk about how Vitest works and provides support for custom runtimes, using Node.js as a driver to run tests in another environment. We'll describe the specifics of our custom Vitest pool, and how we added support for dynamic code evaluation to our runtime. Finally we'll talk about how we improved developer ergonomics with isolated per-test storage, test helpers for accessing Durable Object instances directly, and support for declarative HTTP request mocking., and how we created a service to build types for users' specific compatibility settings.

A deep-dive into how we automatically generate TypeScript definitions for the V8-based runtime that powers Cloudflare Workers. We'll give an overview of how we use the TypeScript compiler API, how we enhance auto-generated definitions with user-written overrides to improve ergonomics, and how we created a service to build types for users' specific compatibility settings.