Each row below is Stable only for its contract. The rest of src/web_api/ is Preview. There is no document, DOM tree, or browser origin in Amber, so several APIs behave like their server-side cousins rather than the browser versions.
| API | Id | Notes |
|---|
fetch, Request, Response, Headers | G9 | Streaming body reader, redirect modes, AbortSignal, integrity. text() and json() are synchronous. response.body is not a ReadableStream instance. |
WebSocket client | G15 | ws:// handshake, text and binary frames. No subprotocols or permessage-deflate. Not a server. |
| API | Id | Notes |
|---|
URL, URLSearchParams | G10 | No IDNA. |
TextEncoder, TextDecoder | G10 | UTF-8 only. |
structuredClone | G10 | The types in the contract, including ArrayBuffer transfer. |
atob, btoa | G29 | Throws Error, not DOMException. |
Blob, File, FormData | G11 | text() and arrayBuffer() return values, not Promises. |
crypto.subtle, crypto.randomUUID, getRandomValues | G14 | SHA, HMAC, AES, PBKDF2, ECDH, Ed25519, ECDSA, RSA. No HKDF, RSA-PSS, or X25519. |
DOMParser | G32 | Read-only parse tree for HTML and XML. Not a live DOM. |
| API | Id | Notes |
|---|
Event, EventTarget, CustomEvent, AbortController | G12 | No tree, so propagation does not cross parents. |
MessageChannel, BroadcastChannel | G12 | Same-isolate delivery. |
ErrorEvent, global onerror | G30 (provisional) | Constructed events are not instanceof Event. |
ReadableStream, WritableStream, TransformStream | G13 | No backpressure from queuing strategies. |
CompressionStream, DecompressionStream | G13 | gzip, deflate, deflate-raw; one member per write. |
setTimeout, setInterval, queueMicrotask, performance | G13 | now, mark, measure. |
| API | Id | Notes |
|---|
Dedicated Worker, worker_threads | G16 | One thread and isolate per worker. Messages are JSON. |
navigator.serviceWorker.register | G16 | Install and activate lifecycle, clients.claim(). |
Service-worker fetch interception | G35 | FetchEvent.respondWith from an activated worker. |
caches (Cache Storage) | G34 | In-process memory store. Not an HTTP cache and not persistent. |
| Background Sync | G33 | Fires on the same isolate. Not Periodic Sync. |
navigator.clipboard.writeText / readText | G31 | Process-local string, not the OS clipboard. |
DOMException, URLPattern, navigator, queuing strategies, ReadableStream.from, amber:sockets, wintercg / wintertc export conditions, and import.meta.main / env / resolve are part of the Stable scope. See WinterTC.
SharedWorker and module workers ({ type: "module" } throws).- Push subscriptions,
Notification, and the Payment Request API.
ClipboardItem read and write (rejects with an error naming ClipboardItem).CacheStorage.match, matchAll, and the ignore* options.