JavaScript Remote Procedure Call (RPC) - Web Socket Adapter

Usage no npm install needed!

<script type="module">
  import ch1RpcWebSocket from 'https://cdn.skypack.dev/@ch1/rpc-web-socket';




This is not well maintained

This is not traditional RPC, but it is like it


yarn add @ch1/rpc-web-socket


This library has an external optional run time dependency for the server side portion, which leverages the excellent ws library.

The dependency is optional in that this library will work with anything that satisfies the ws interface:

export type WsWebSocket = {
  on: (message: string, callback: (data: any) => any) => any;
  send: (data: string) => any;

We do include ws as a devDependency since we use it for testing the library end to end.


Slightly easier API than in the raw @ch1/rpc

Client JS Script (using the function foo on the server)

const ws = new WebSocket('ws://localhost:8080');
const rpc = wrpc.create({ socket: ws });

rpc.ready.then(() => rpc.remote.foo()).then(result => {

Server JS (sharing the function foo to the client)

const WebSocket = require('ws');
const wrpc = require('@ch1/rpc-web-socket');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', ws => {
    { socket: ws },
      foo: () => new Promise(resolve => resolve(7)),

Error Handling

Due to the nature of state that could exist on client/server, this library takes the approach of terminating itself in the event of catastrophic failure.

  • Individual functions that fail are left up to the user to handle
  • Connection failures will result in the destruction of the object
  • Pending async requests will have their error handlers triggered

best practice is to add an error listener:

const wrpc = require('@ch1/rpc-web-socket');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', ws => {
  const rpc = wrpc.create(
    { socket: ws },
      foo: () => new Promise(resolve => resolve(7)),

  // This is teh relevant bit
  rpc.onDestroy((reason?: string) => {
    // put your error handling logic here.

Web Socket Connection Handling

This library attempts to automatically handle all connection errors and fail fast where possible. This includes a server side "ping pong" to detect "unplug" events.

Reconnection Is Left Up To The User of The Library, onDestroy is your friend

Presumably the client will be responsible for the reconnection.


The create function will provide an RPC<RemoteType> object:

export function create<RemoteType>(
  // required
  config: RPCSocketConfig,

  // functions (optionally nested) to provide to other side of the connection
  remote?: Remote<any>,

  // not used for now
  remoteDesc?: RemoteDesc,
) {

The RPCSocketConfig object looks like:

export interface RPCSocketConfig {
  // optionally configure the ping/pong delay the server uses
  // defaults to 10,000ms
  pingDelay?: number;

  // *mandatory* the socket to use, either WebSocket in the browser
  // or something _like_ `ws` on the server
  // (we're ws 6.x compatible)
  socket: NativeWebSocket | WsWebSocket;

The RPC<RemoteType> object is described in the documentation for @ch1/rpc