Simple websocket API

sock.js

/* Simple WebSocket API.
 * Dependencies: none.
 *
 * Message fields:
 * msgid: server replies must match this
 * data: the actual data
 *
 * Interface in a nutshell:
 * - var sd = sock.open("ws://host:port", open_callback)
 * - sock.send(sd, data, reply_callback);
 * - sock.on(sd, event_name, event_callback);
 * - sock.off(sd, event_name);
 * - sock.close(sd);
 *
 * Basic demo:
 * sock.open("ws://host:post", (sd) => {
 *	sock.on(sd, "message", (msg) => {
 *		console.log("got message", sd, msg);
 *	});
 *	sock.send(sd, {foo:"bar"});
 * });
 *
 * To understand everything else, start reading the open().
 */
/*
sock.open("ws://host:post", (sd) => {
	console.log("sock.open()", sd);
	sock.on(sd, "message", (msg) => {
		console.log("got message", sd, msg);
	});
});
*/
(() => {
"use strict";

var sockets = [];

function on(sd, ev, cb) {
	sockets[sd].evs[ev] = cb;
}

function off(sd, ev) {
	delete sockets[sd].evs[ev];
}

function onmsg(sd, ev) {
	var d, cb;

	d = JSON.parse(ev.data);
	if(sockets[sd].evs[ev.type])
		sockets[sd].evs[ev.type](d);
	cb = sockets[sd].cbs[d.id];
	if(cb) {
		delete sockets[sd].cbs[d.id];
		cb(d);
	}
}

function close(sd) {
	sockets[sd].ws.close();
}

function open(uri, cb) {
	var sd = sockets.length, ws;

	if(!(uri && cb))
		return;
	ws = new WebSocket(uri);
	ws.onopen = ((ev) => cb(sd));
	ws.onclose = ((ev) => delete sockets[sd]);
	ws.onerror = ((ev) => console.log("ERROR", ev));
	ws.onmessage = ((ev) => onmsg(sd, ev));
	sockets[sd] = {
		ws: ws,
		msgid: 0,
		cbs: {},
		evs: {}
	}
	return sd;
}

function send(sd, data, cb) {
	data.msgid = ++sockets[sd].msgid;
	sockets[sd].cbs[data.msgid] = cb;
	sockets[sd].ws.send(JSON.stringify(data));
}

window.sock = {
	open: open,
	send: send,
	close: close,
	on: on,
	off: off
}
})();