# Web APIs

Beyond ECMAScript itself, Phasis ships several layered packs of WHATWG / W3C APIs:

- **Web Platform Pack** — pure value types, no I/O: `URL`, `URLSearchParams`, `URLPattern`, `TextEncoder`, `TextDecoder`, `atob`, `btoa`, `structuredClone`, `performance`, `DOMException`.
- **Fetch Pack** — real HTTP from JavaScript: `fetch`, `Request`, `Response`, `Headers`, `Body`, `AbortController`, `AbortSignal`, `Blob`, `File`, `FormData`, `EventTarget`, `Event`, full WHATWG Streams (`ReadableStream`, `WritableStream`, `TransformStream`, queuing strategies, BYOB), `CompressionStream` / `DecompressionStream` (gzip / deflate / deflate-raw via zlib; brotli when the `kjdev/php-ext-brotli` PECL extension is loaded), `navigator`, and the HTML-spec `self` global alias + `reportError`.
- **Crypto** — `crypto.getRandomValues`, `crypto.randomUUID`, and full `SubtleCrypto`: digest (SHA-1/256/384/512), HMAC, AES-GCM/CBC/CTR, RSA-OAEP/PSS/PKCS1, ECDSA (P-256/384/521), ECDH, HKDF, PBKDF2 — plus JWK import/export. Backed by `ext-openssl`.
- **WebSocket** — constructor, RFC 6455 frame codec, events. Default transport uses `stream_socket_client`; replaceable via `Engine::setWebSocketTransport()` for ReactPHP / Ratchet / mocks in tests.
- **XMLHttpRequest** — layered over the fetch transport, so the same policy hooks and swappable transport apply.
- **Event loop** — `setTimeout`, `setInterval`, `clearTimeout`, `clearInterval`, `queueMicrotask`. Plus `AsyncContext` (Stage 3) propagating values across microtask / timer boundaries.

All packs are **on by default**. No flag, no setup — `typeof fetch` returns `"function"` on a fresh `new Engine()`.

## Conformance

The imported [Web Platform Tests](https://github.com/web-platform-tests/wpt) corpus (`tests/Wpt/fixtures/`) covers `AbortController` / `AbortSignal`, `atob` / `btoa`, `Blob` / `File`, `TextEncoder` / `TextDecoder`, `EventTarget` / `Event`, `FormData`, `Headers`, `performance.now`, the full Streams Standard (`Readable`/`Writable`/`Transform` + BYOB + queuing), `structuredClone`, `URL` / `URLSearchParams`, the full **`crypto` / `SubtleCrypto`** surface (digest, HMAC, AES-GCM/CBC/CTR, RSA-OAEP/PSS/PKCS1, ECDSA, ECDH, HKDF, PBKDF2 — including thousands of derive-bits permutations from `hkdf` and `pbkdf2`), the **`WebSocket`** state machine (constructor URL and subprotocol validation, close-code semantics, `send()` for strings / `ArrayBuffer` / typed-array views / `Blob`, `binaryType`, `bufferedAmount`, async close while connecting, event-handler nullability), and a broad slice of **`Fetch`** + **`XMLHttpRequest`** — `responseType` state machine, abort/send transitions, CORS-safelisted headers, multipart `FormData` uploads, `XMLHttpRequestUpload` + `ProgressEvent`, `Response`/`Headers` init validation, the static `Response.json` / `Response.error` constructors, redirect-chain Authorization stripping, `URL.createObjectURL` blob URLs, body-mixin consumption (`text` / `blob` / `json` / `formData` / `arrayBuffer`), `Response.clone` with `structuredClone`-d teed streams, and sync XHR network-error throwing. Every imported subtest passes.

To extend further, drop a new `*.any.js` into `tests/Wpt/fixtures/<category>/` — the runner picks it up automatically. The XHR/Fetch suites are driven by `tests/Wpt/fetch-server.php` (a single-file emulator of the WPT `resources/*.py` handlers); the WebSocket suite uses an inert in-runner transport that synthesizes open/echo/close, sufficient for the imported fixtures. Run the corpus yourself:

```bash
bin/wpt                # everything
bin/wpt --category headers --verbose   # one area, per-subtest output
bin/wpt --json         # machine-readable
```

## fetch() example

```js
const res = await fetch("https://api.example.com/users", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ name: "alice" }),
});
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const user = await res.json();
```

That works out of the box. The default transport is PHP `ext-curl`. Bodies stream through the WHATWG `ReadableStream` Phasis ships, so `for await (const chunk of res.body)` also works.

## AbortController example

```js
const ctrl = new AbortController();
setTimeout(() => ctrl.abort(), 5000);
try {
  const res = await fetch(slowUrl, { signal: ctrl.signal });
} catch (e) {
  if (e.name === "AbortError") {
    // request was cancelled
  }
}
```

`AbortSignal.timeout(ms)` is also implemented (lazy-deadline — checks on `aborted` read rather than firing an event mid-event-loop; works for fetch transports that poll the signal during transfer).

## Embedder controls (PHP side)

Three hooks on the `Phasis\Engine` class control fetch behavior:

```php
$engine = new Phasis\Engine();

// 1. Swap the HTTP transport. The callable receives a request descriptor
//    and an optional AbortSignal; returns a response descriptor.
$engine->setFetchTransport(function (array $request, $signal) {
    // ... use Guzzle, Symfony HttpClient, your stub, etc.
    return [
        'status' => 200,
        'statusText' => 'OK',
        'headers' => [['content-type', 'application/json']],
        'body' => '{"data":"value"}',
    ];
});

// 2. Pre-flight policy hook — rewrite, deny, or allow.
$engine->setFetchPolicy(function ($request) {
    $url = $request->get('url')->value;
    if (!str_starts_with($url, 'https://')) {
        throw new \RuntimeException('HTTPS only');
    }
    return null;  // allow as-is; return modified Request to rewrite
});

// 3. Cookie jar. Opt-in. Accepts any object with get(url):string and
//    set(url, header):void methods. JsObject or PHP object both work.
$engine->setCookieJar($myJar);
```

If `setFetchTransport()` is not called, the default `CurlTransport` runs. The cookie jar is **opt-in** — no default jar, no cookies stored unless you provide one.

## Streams example

```js
// Producer: ReadableStream that yields numbers 1..5
const rs = new ReadableStream({
  start(controller) {
    for (let i = 1; i <= 5; i++) controller.enqueue(i);
    controller.close();
  },
});

// Consumer: async iteration
for await (const value of rs) {
  console.log(value);  // 1, 2, 3, 4, 5
}

// Pipe through a transform
const ts = new TransformStream({
  transform(chunk, controller) { controller.enqueue(chunk * 2); },
});
const doubled = new ReadableStream({
  start(c) { [1, 2, 3].forEach(n => c.enqueue(n)); c.close(); }
}).pipeThrough(ts);
for await (const v of doubled) console.log(v);  // 2, 4, 6
```

Full Streams spec: `ReadableStream`, `WritableStream`, `TransformStream`, `ReadableStreamDefaultController`, `ReadableByteStreamController`, `ReadableStreamDefaultReader`, `ReadableStreamBYOBReader`, `ReadableStreamBYOBRequest`, `WritableStreamDefaultController`, `WritableStreamDefaultWriter`, `TransformStreamDefaultController`, `ByteLengthQueuingStrategy`, `CountQueuingStrategy`, plus `pipeTo` / `pipeThrough` / `tee`.

## Event loop

`setTimeout`, `setInterval`, `clearTimeout`, `clearInterval`, and `queueMicrotask` are on the global object. Microtasks (Promise handlers, `queueMicrotask`) drain to completion between every macrotask; timers fire in deadline order via a per-realm queue.

```js
console.log('sync');
queueMicrotask(() => console.log('microtask'));
setTimeout(() => console.log('timer'), 0);
// → sync, microtask, timer

const id = setInterval(() => console.log('tick'), 1000);
// ...later
clearInterval(id);

await new Promise(r => setTimeout(r, 50));   // common "delay" pattern works
```

Driven by Phasis's `Engine::runEventLoop()`, which `eval()` and `evalAsModule()` call automatically after the synchronous code finishes. The loop is **virtual-time** by default — `setTimeout(cb, 5000)` does not sleep PHP; the loop advances its clock to the deadline so the program completes promptly. Real-time embedders drive `tickEventLoop()` themselves. See [API: Event loop](/docs/api#event-loop) for the host-side surface.

## What's *not* shipped

These browser-only or runtime-model APIs are deliberately out of scope — see [Known limitations](/docs/compatibility/limitations) for the full discussion:

- `window`, `document`, the DOM tree
- `localStorage`, `sessionStorage`, `IndexedDB`
- `Worker`, `SharedWorker`, `MessageChannel`
- Service Workers, Push API, Notifications, BroadcastChannel

Most of these can be polyfilled by the embedder via `$engine->setGlobal()` if needed.

## Growing the WPT corpus

`tests/Wpt/upstream/` is a sparse-checkout of [web-platform-tests/wpt](https://github.com/web-platform-tests/wpt) covering `fetch/`, `streams/`, `FileAPI/`, `xhr/formdata/`, `dom/abort/`, `dom/events/`. To extend coverage: copy any `*.any.js` file from `upstream/<area>/` into `tests/Wpt/fixtures/<category>/`. The runner picks it up on next run; failures get logged via `bin/wpt --verbose`.