Extension Port Stream

A module for creating a Node-style stream over a WebExtension Runtime.Port object.

Breaking changes from v4 to v5

1. Chunking mode is enabled by default (see the Usage section below).
2. Node.js-style Buffer messages are no longer supported.

Additionally, the timing of logging, errors, and callbacks may be handled differently.

Usage

By default, ExtensionPortStream will send messages in 64MB chunks on Chromium-based browsers. When this mode is used the receiving end must also use ExtensionPortStream in its default mode.

import { ExtensionPortStream } from "extension-port-stream";

extension.runtime.onConnect.addListener(connectRemote);
const portStream = new ExtensionPortStream(remotePort, {
  chunkSize: 0, // disable chunking
});

// Enjoy!

To disable chunking set the chunkSize option to 0. This will make the transport mostly backwards compatible with v4.

import { ExtensionPortStream } from "extension-port-stream";

extension.runtime.onConnect.addListener(connectRemote);
const portStream = new ExtensionPortStream(remotePort, {
  chunkSize: 0, // disable chunking
});

// Enjoy!

Events

ExtensionPortStream extends Node.js Duplex stream, so it inherits all EventEmitter capabilities. Additionally, it emits the following custom events:

message-too-large

Emitted when a message is too large to send in a single postMessage call and needs to be chunked. This event is only emitted when chunking is enabled (default).

import {
  ExtensionPortStream,
  MessageTooLargeEventData,
} from "extension-port-stream";

const portStream = new ExtensionPortStream(remotePort);

portStream.on("message-too-large", (data: MessageTooLargeEventData) => {
  console.log(
    `Message too large (${
      JSON.stringify(data.message).length
    } bytes), chunking into ${data.chunkSize}-byte pieces`
  );
  console.log("Original error:", data.originalError.message);
});

Running tests

yarn test