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OpenOrange
Runtime APIs / Runtime globals

Runtime APIs

Runtime globals

How OpenOrange installs and validates Cloudflare Workers globals in Node.js.

Status: Partial

Configuration

OpenOrange runs one fixed compatibility profile: compatibility date 2026-09-03 with nodejs_compat. No OpenOrange-specific configuration is required.

OpenOrange ignores compatibility_date and compatibility_flags in the Wrangler file. Worker code should behave as it does on Node.js, so OpenOrange does not switch runtime behavior by date or flag. orange dev prints a startup warning that lists each flag it does not apply. The assets_navigation_prefers_asset_serving flags are the only exception. See Static assets.

How it works

OpenOrange intersects value-bearing declarations with the globals exposed across the pinned workerd global prototype chain. The current profile contains 83 Cloudflare global names. Before loading the Worker entrypoint, the runtime installs a manifest with exactly those names.

  • atob, btoa, queueMicrotask, TextEncoder, and TextDecoder are implemented.
  • Headers, Request, Response, URL, URLSearchParams, Blob, DOMException, Event, ReadableStream, WritableStream, TransformStream, console, and the four timer functions are partial implementations backed by pinned Undici or Node.js primitives.
  • Outbound fetch() converts Orange requests to that pinned Undici substrate and wraps its response back into the Worker-compatible response.
  • performance and structuredClone() use the captured Node.js web-platform implementations, and WebAssembly exposes the captured Node.js namespace.
  • console forwards to the Node.js console captured before Worker globals are installed, so Worker diagnostics reach orange dev output.
  • Unhandled promise rejections are reported as background diagnostics without terminating the shared runtime process.
  • The global scope dispatches unhandledrejection and rejectionhandled events, as workerd does.
  • WebSocket supports outbound client connections for RivetKit and Cap’n Web.
  • WebSocketPair now creates two entangled Worker endpoints with acceptance, queued delivery, copied text and binary frames, current close validation, close events, and the latest default close auto-reply behavior.
  • Response accepts a pair endpoint with status 101 and exposes it through response.webSocket; the runtime couples that endpoint to real client and Durable Object transport connections.
  • serializeAttachment() and deserializeAttachment() work on WebSocket endpoints.
  • Timers return browser-style numeric identifiers from one shared pool, and either clear function can cancel a timeout or interval.
  • The runtime captures these Node.js constructors and functions before installing the Cloudflare manifest so the HTTP substrate, Cap’n Web, and RivetKit continue to use compatible host primitives.
  • Until Worker code has its own thread, hidden ref(), unref(), and refresh() methods on numeric timer values bridge Node libraries that dynamically expect timer handles.

crypto delegates standard Web Crypto operations to Node.js and supplies the Cloudflare structural extensions used by current Workers types: subtle.timingSafeEqual() and streaming SHA-1, SHA-256, SHA-384, and SHA-512 digests through crypto.DigestStream.

  • The HTTP globals support normalized headers, repeated Set-Cookie values, buffered request and response bodies, cloning, the body readers, and the basic Response.error(), Response.redirect(), and Response.json() constructors.
  • Status-101 WebSocket responses retain their socket and reject cloning, a non-null body, a missing socket, or a non-101 status using the pinned workerd behavior.
  • URL parsing, mutation, query iteration, and live searchParams mutation are supported.
  • Other globals keep the Node.js host value when Node.js provides one, such as TextDecoderStream and the streams queuing strategies.
  • The rest install as throwing placeholders.
  • Calling, constructing, or reading a property from a placeholder produces a clear unimplemented error.

A ReadableStream body is used as is, so it locks only when the body is read. Reading it accepts any ArrayBuffer or ArrayBufferView chunk, as workerd does, and an iterable body becomes a stream whose cancel() calls the iterator’s return().

When Orange sends a response whose Content-Encoding is exactly gzip or br, it compresses the body and drops Content-Length, as workerd does. A response created with encodeBody: "manual" already holds encoded bytes, so Orange sends them as they are. This applies to Worker responses, Durable Object fetch() responses, and service binding responses, whose callers read the decoded body.

A byte ReadableStream that does not set autoAllocateChunkSize gets workerd’s default of 4096 bytes, so a default read still exposes controller.byobRequest. queueMicrotask(), setTimeout(), and setInterval() reject a non-function callback when they are called.

The encoding and HTTP implementations delegate their substrate behavior to Node.js while conforming to the pinned Cloudflare constructors. Partial values must be assignable to the complete Cloudflare contract; fully implemented values additionally require exact inferred types.

Conformance

  • The conformance check verifies the global manifest has no missing or extra Cloudflare names, verifies supported values against the reference contract, and runs behavior fixtures against the pinned Cloudflare runtime.
  • The HTTP fixture compares header iteration and Set-Cookie handling, buffered request bodies, cloning, response constructors, status metadata, and exact tested errors.
  • The WebSocket fixture compares pair shape, upgrade responses, queued text and binary frames, close validation, event data, ready states, and close auto-reply.
  • The check also verifies that the manifest is installed before the Worker module evaluates.

Deviations

  • Node-specific globals without Cloudflare counterparts remain available at runtime but are not included in generated Worker types.
  • Custom request fetchers and the encodeResponseBody request option are not implemented. Blob and FormData bodies work.
  • fetch() decodes deflate response bodies through undici. Workerd decodes only gzip and br, and passes other codings through.
  • URL.createObjectURL() is not implemented.
  • These are not implemented: custom fetchers, Cloudflare-specific outbound request metadata, some Cloudflare crypto algorithms, exact stream queuing semantics, exact timer delay, scheduling and resource-limit behavior, performance-entry semantics, and structured-clone host types.
  • Unimplemented Cloudflare globals without a Node.js host value throw instead of providing partial behavior. Host values are Node.js behavior, not verified workerd behavior.
  • Unhandled rejections are diagnosed and dispatched as unhandledrejection events. An exception thrown from a timer, microtask, or event listener is diagnosed the same way and does not stop the runtime process.