net-web

Virtual TCP sockets for the browser. A shim for Node's net module that uses in-memory EventEmitters instead of real network connections.

Why?

Browsers can't open TCP sockets. This module provides a virtual socket layer that allows code written for Node's net module to work in the browser. When paired with http-web and hsync, you can run an HTTP server entirely in a browser tab.

Installation

npm install net-web

Usage

Creating a Server

const net = require('net-web');

const server = net.createServer((socket) => {
  console.log('Client connected');

  socket.on('data', (data) => {
    console.log('Received:', data);
    socket.write('Echo: ' + data);
  });

  socket.on('close', () => {
    console.log('Client disconnected');
  });
});

server.listen(3000);

Creating a Client

const net = require('net-web');

const socket = net.Socket();

socket.on('data', (data) => {
  console.log('Server says:', data);
});

socket.connect(3000, 'localhost', () => {
  socket.write('Hello server!');
});

Closing a Server

server.close(() => {
  console.log('Server closed');
});

API

net.createServer(connectionListener)

Creates a virtual server. The connectionListener is called for each incoming connection with a socket object.

Returns a server object with:

• listen(port) - Start listening on a virtual port
• close([callback]) - Stop listening and clean up

net.Socket()

Creates a virtual client socket.

Returns a socket object with:

• connect(port, [host], [callback]) - Connect to a server
• write(data) - Send data to the connected server
• end() - Close the connection
• on(event, callback) - Listen for events ('data', 'close')

net.events

The shared EventEmitter used for routing connections. Exposed for advanced use cases.

net.servers

Map of active servers by port. Exposed for debugging.

How It Works

Instead of real TCP connections, net-web uses a shared EventEmitter to route data between sockets:

1. server.listen(port) registers a listener for socket_connect_{port} events
2. socket.connect(port) emits a socket_connect_{port} event
3. The server creates a paired socket and calls the connection handler
4. socket.write() emits data events on the paired socket
5. socket.end() emits close events

All communication is synchronous and in-memory. The "port" is just an identifier for matching clients to servers.

Global State

The module maintains global state via globalThis.nodeNetWeb so that multiple modules importing net-web share the same event bus. This allows http-web to communicate with hsync through the same virtual ports.

License

ISC