Socket

Socket is a typed wrapper around WebSocket. Unlike a direct WebSocket, send() can be called before the connection opens, and messages are sent after open. Incoming data is deserialized into message.

Example: Notification Channel

import { createSocket } from "mobx-swiss-knife";

type Notification = { type: 'notification'; text: string };
type Command = { type: 'subscribe'; channel: string };

const socket = createSocket<void, Notification, Command>({
  url: 'wss://example.com/ws',
  deserializeInputMessage: (raw) => JSON.parse(raw) as Notification,
  serializeOutputMessage: (message) => JSON.stringify(message),
  reconnect: {
    enabled: true,
    timeout: 2000,
  },
});

socket.open();
socket.send({ type: 'subscribe', channel: 'news' });

console.log(socket.isOpen);
console.log(socket.message);

socket.close();
socket.destroy();

A message sent before the actual OPEN is placed in the internal queue. destroy() ends the lifecycle and cancels reconnect; call it when the owner is removed.

URL with a Payload

const socket = createSocket<{ token: string }, Incoming, Outgoing>({
  url: ({ token }) => `wss://example.com/ws?token=${token}`,
});

socket.open({ token: auth.token });

Properties

• isOpen — whether the connection is currently in the OPEN state.
• message — the last successfully parsed incoming message or null.
• isReconnectEnabled — whether reconnect is enabled.

Methods and Options

• open(payload?) — open the connection; the payload is passed to the url function.
• send(message) — send or queue a message.
• close(code?) — close with the specified code; defaults to 1000.
• resendNotSentMessages() — manually send the accumulated queue.
• getSocketUrl(payload) — get the final URL without opening the connection.
• destroy() — cancel the lifecycle.
• reconnect: { enabled, timeout?, skipCodes? } — reconnect; close codes 1001 and 1005 are skipped by default.