Table of contents

websockets

open websocket

ws = new WebSocket(url);

sending a message

ws.send('hello world!');

events

on message

ws.onmessage = function(e) {
	console.log('received message: ' + e.data);
}

on open

ws.onopen = function() {
	console.log('socket open');
}

on close

ws.onclose = function() {
	console.log('closing socket');
}

checking whether or not a socket exists and is open

if(typeof ws !== 'undefined' && ws.readyState === WebSocket.OPEN) {
	...
}

documentation

https://developer.mozilla.org/en-US/docs/Web/API/WebSocket

ping - pong

browsers don't currently have an implementation of a ping method, you can at best define a custom message

ws.send('ping');

browsers will automatically respond to a ping with a pong

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers#pings_and_pongs_the_heartbeat_of_websockets

links

websocket documentation

https://developer.mozilla.org/en-US/docs/Web/API/WebSocket

websockets echo service

http://eriklievaart.com/web/websockets.html
https://www.websocket.org/echo.html