socket.io-client

What is socket.io-client?

The socket.io-client npm package is a client-side library that enables real-time, bidirectional and event-based communication between web clients and servers. It works on every platform, browser or device, focusing equally on reliability and speed.

What are socket.io-client's main functionalities?

Connecting to a server

This code sample demonstrates how to connect to a Socket.IO server running on localhost at port 3000.

const io = require('socket.io-client');
const socket = io('http://localhost:3000');

Emitting events

This code sample shows how to emit an event to the server with an event name and associated data.

socket.emit('event_name', { some: 'data' });

Listening for events

This code sample illustrates how to listen for events emitted by the server and handle them with a callback function.

socket.on('event_name', function(data) {
  console.log(data);
});

Disconnecting from the server

This code sample shows how to handle a disconnection event when the client gets disconnected from the server.

socket.on('disconnect', function() {
  console.log('Disconnected from server');
});

Other packages similar to socket.io-client

ws

The 'ws' package is a simple to use, blazing fast, and thoroughly tested WebSocket client and server implementation. Unlike socket.io-client, which provides an abstraction over WebSocket with additional features like auto-reconnection, 'ws' is a bare WebSocket implementation.

faye-websocket

Faye is a set of tools for simple publish-subscribe messaging between web clients. It's similar to socket.io-client in that it provides an abstraction over WebSocket for real-time communication, but it has a different API and feature set.

sockjs-client

SockJS-client is a browser JavaScript library that provides a WebSocket-like object. SockJS gives you a coherent, cross-browser, Javascript API which creates a low latency, full duplex, cross-domain communication channel between the browser and the web server, with WebSockets or without. It is similar to socket.io-client but focuses more on providing fallback options for environments where WebSocket is not available.

README

socket.io-client

How to use

A standalone build of socket.io-client is exposed automatically by the socket.io server as /socket.io/socket.io.js. Alternatively you can serve the file socket.io.js found in the dist folder or include it via CDN.

<script src="/socket.io/socket.io.js"></script>
<script>
  var socket = io();
  socket.on('connect', function(){});
  socket.on('event', function(data){});
  socket.on('disconnect', function(){});
</script>

// with ES6 import
import io from 'socket.io-client';

const socket = io();

A slim build (without debug) is also available: socket.io.slim.js.

Socket.IO is compatible with browserify and webpack (see example there).

Node.JS (server-side usage)

Add socket.io-client to your package.json and then:

var socket = require('socket.io-client')('http://localhost:3000');
socket.on('connect', function(){});
socket.on('event', function(data){});
socket.on('disconnect', function(){});

Debug / logging

In order to see all the client debug output, run the following command on the browser console – including the desired scope – and reload your app page:

localStorage.debug = '*';

And then, filter by the scopes you're interested in. See also: https://socket.io/docs/logging-and-debugging/

API

See API

License

MIT