wintertc

Portable Web APIs in a TypeScript component

This example exercises Web Platform APIs that are commonly available across server-side JavaScript runtimes. These APIs broadly follow the WinterTC Minimum Common Web Platform API and are provided during componentization by StarlingMonkey. The example is both a usage reference and an end-to-end regression test for Jco when its componentize-js dependency changes.

The component exposes a manually implemented wasi:http/incoming-handler using the familiar Service Worker fetch event pattern. The small HTTP adapter lives in http.ts, and each built-in check has its own module under builtins. component.ts brings the checks together and returns their pass/fail results as JSON for each request:

• URL and URLSearchParams
• TextEncoder, TextDecoder, atob, and btoa
• crypto.getRandomValues, crypto.randomUUID, and crypto.subtle.digest
• performance.now
• Blob, File, and FormData
• structuredClone
• EventTarget, CustomEvent, AbortController, DOMException, timers, and queueMicrotask
• ReadableStream, TransformStream, CompressionStream, and DecompressionStream
• Headers, Request, and Response

Run the example

Install the repository dependencies, then build the component and run its checks in both Node.js and Deno:

pnpm install
pnpm run all

The Node.js check runs the component with jco serve. The Deno check launches jco serve inside Deno, ensuring the transpiled component and its WASI host shims work there too. You can run them separately with pnpm run demo:node and pnpm run demo:deno after building.

Runtime boundaries

Web Platform APIs do not imply Node.js compatibility. Component code cannot import node:fs, other node: modules, or native Node.js addons. Use portable Web APIs and explicit WIT/WASI interfaces instead of runtime-specific globals and modules.

This example currently exports WASI HTTP Preview 2 (wasi:http@0.2.10). It cannot move to Preview 3 yet because the current componentize-js/StarlingMonkey backend does not support componentizing Preview 3 WIT worlds. This is a componentization-toolchain limitation; the Web Platform APIs demonstrated here are not inherently Preview 2 APIs.