data-transport

data-transport orchestrates request-response messaging across iframes, workers, browser extensions, Node.js processes, Electron, BroadcastChannel, and WebRTC peers with one consistent API. Each transport handles connection setup, timeouts, and logging so you can focus on your payloads.

Table of Contents

• data-transport unlocks cross-context messaging
• Why data-transport reduces boilerplate
• Install the package
• Start with a request-response example
• Understand how transports are organized
• Combine advanced capabilities when you need them
• Run the examples locally
• Develop and contribute with confidence

data-transport unlocks cross-context messaging

The library exposes a small set of composable primitives: a base Transport class, the createTransport factory, decorators for registering listeners, and helpers for merging or mocking transports. All transports enforce the same request-response contract, share timeout handling, and use unique identifiers under the hood to avoid collisions.

Why data-transport reduces boilerplate

• One API everywhere. Swap the transport key to reuse the same emit and listen code across iframes, workers, extensions, WebRTC, BroadcastChannel, or Node.js child processes.
• Bi-directional by default. Every emit returns a promise, and listeners can opt out of responding for fire-and-forget events.
• Connection-aware transports. Iframe, worker, and browser-extension transports delay sends until the peer reports that it is ready, exposing onConnect and onDisconnect hooks when the runtime supports them.
• Structured logging and serialization. Pass serializer, timeout, prefix, and logger options once to standardize payload formatting and diagnostics.
• Testing-friendly helpers. mockPorts() provides in-memory listeners for unit tests, while merge() fans out messages to multiple transports without re-registering listeners.

Install the package

Install from npm or yarn and let TypeScript discover the included type definitions.

npm install data-transport
# or
yarn add data-transport
# or
pnpm add data-transport

Start with a request-response example

Define interaction types:

type Internal = {
  hello(options: { num: number }, word: string): Promise<{ text: string }>;
};

Create transport in main page:

import { createTransport } from 'data-transport';

const external = createTransport<'IFrameMain', { listen: Internal }>('IFrameMain');
external.listen('hello', async (num) => ({ text: `hello ${num}` }));

Create transport in the iframe:

import { createTransport } from 'data-transport'

const internal = createTransport<'IFrameInternal', { emit: Internal }>('IFrameInternal');
expect(await internal.emit('hello', { num: 42 }, 'Universe')).toEqual({ text: 'hello 42 Universe' });

Understand how transports are organized

createTransport(name, options) instantiates the matching transport class. The table lists the available keys and highlights when to use them.

Transport key	Runtime	Highlights
MessageTransport	Any window	Uses window.postMessage for simple page-to-page messaging.
IFrameMain	Host window	Targets a specific iframe, includes handshake and reload handling.
IFrameInternal	Iframe window	Connects back to the parent and syncs on reload.
Broadcast	Modern browsers	Wraps BroadcastChannel, configurable channel name or instance.
WebWorkerClient	Main thread	Sends transferable objects to a Worker, exposes onConnect.
WebWorkerInternal	Worker thread	Mirrors the client transport and queues emits until connected.
SharedWorkerClient	Page connected to a SharedWorker	Auto-sends connect and disconnect signals, exposes onConnect.
SharedWorkerInternal	Shared worker	Tracks ports, broadcasts to all clients, and surfaces onConnect/onDisconnect.
ServiceWorkerClient	Page controlled by a service worker	Handles Safari serialization quirks via the useOnSafari flag.
ServiceWorkerService	Service worker	Routes responses back to the correct client, supporting _clientId.
BrowserExtensions	Generic extension context	Bridges browser.runtime.sendMessage to transports.
BrowserExtensionsMain	Background/service worker script	Manages ports and emits connect/disconnect callbacks.
BrowserExtensionsClient	Content script or popup	Connects over runtime.connect, supports onConnect.
ElectronMain	Electron main process	Uses IPC to communicate with renderer windows.
ElectronRenderer	Electron renderer process	Talks back to the main process over the same channel.
WebRTC	WebRTC data channel	Chunks large payloads, queues writes when buffers fill.
MainProcess	Node.js parent process	Wraps child.send/child.on.
ChildProcess	Node.js child process	Wraps process.send/process.on.

Each transport accepts the generic TransportOptions so you can override listener, sender, timeout, serializer, or logger to match your environment.

Know What TransportOptions Controls

Option	Required	Default	Purpose
listener: (callback) => (() => void) | void	Yes	—	Attach a low-level event handler to the underlying channel. Return a disposer to avoid warnings from the constructor’s safety checks.
sender: (message) => void	Yes	—	Deliver outbound messages. Remove the transfer array before forwarding if the runtime demands it.
timeout: number	No	60000 (ms)	Max wait before an emit rejects with a timeout warning when a response is expected.
verbose: boolean	No	false	Switch on structured logging for every send/receive. Use logger to pipe it elsewhere; otherwise console.info is used.
prefix: string	No	DataTransport	Namespace for action names. Helpful when multiple transports share the same channel.
listenKeys: string[]	No	[]	Class method names that should be auto-registered as listeners. In dev builds, calling them directly throws to prevent misuse.
checkListen: boolean	No	true	Keep dev-time guards that surface duplicate responses or missing listener decorators. Toggle off to silence those warnings in production.
serializer: { stringify?: (data) => string; parse?: (text) => any }	No	—	Supply custom codecs for runtimes with serialization constraints (e.g., structured cloning gaps). Both functions are optional, so you can enable only one direction.
logger: (options) => void	No	—	Replace the default verbose logger. Receives the raw request/response payload for auditing.

Every custom transport you construct via createTransport simply forwards these options to the base Transport class, so you can rely on them in any environment (browser, worker, Node.js, or extensions).

Combine advanced capabilities when you need them

Decorate listeners to register once

Use the provided @listen decorator to attach class methods as listeners without exposing them for manual calls.

import { Transport, listen, mockPorts } from 'data-transport';

const ports = mockPorts();

class ExternalTransport extends Transport {
  constructor() {
    super(ports.create());
  }

  @listen
  async ping() {
    return 'pong';
  }
}

Emit with fine-grained control

emit accepts either the event name or an options object. Set respond: false for fire-and-forget events, change timeout, pass silent to suppress timeout warnings, and use _extra to forward metadata without polluting your payload.

await transport.emit(
  { name: 'notify', respond: false, _extra: { source: 'dashboard' } },
  { status: 'ready' }
);

Merge transports to broadcast widely

merge(first, second, ...others) combines transports so all listeners receive the same events while respecting the shared timeout, serializer, and logger.

import { createTransport, merge } from 'data-transport';

const broadcast = createTransport('Broadcast', {});
const serviceWorker = createTransport('ServiceWorkerClient', { worker });
const merged = merge(broadcast, serviceWorker);

await merged.emit('announce', { version: '5.0.3' });

Mock ports to test without a runtime

mockPorts() provides in-memory listener/sender pairs so you can assert end-to-end flows in Jest or any node-based test runner.

const ports = mockPorts();
const internal = createTransport('Base', ports.main);
const external = createTransport('Base', ports.create());

Rely on built-in connection lifecycles

Iframes, workers, browser extensions, and shared workers expose .onConnect() (and .onDisconnect() where supported) so you can delay expensive initialization until a peer is actually present. WebRTC transports buffer messages when the data channel is saturated and replay them once the browser signals that the buffer dropped below bufferedAmountLow.

Run the examples locally

Real-world samples live in the examples directory, covering BroadcastChannel, browser extensions, Electron, iframes, Node.js, service workers, shared workers, WebRTC, and web workers.

• Clone the repository.
• Install dependencies with yarn.
• Run the example you care about by opening the matching folder (for example, examples/webworker) and following the instructions documented inside.
• Try the hosted BroadcastChannel demo on CodeSandbox: data-transport Broadcast example.

Develop and contribute with confidence

• yarn build compiles TypeScript and bundles the distributable with Rollup.
• yarn test executes the Jest suite, including transport handshakes and serializer scenarios.
• yarn clean removes build artifacts, while yarn prettier enforces formatting in src.
• The project ships type definitions (dist/index.d.ts) so downstream TypeScript projects get autocomplete out of the box.

License

MIT