socket.io/lib/socket.js

/**
 * Module dependencies.
 */

var parser = require('socket.io-parser');
var Emitter = require('component-emitter');
var toArray = require('to-array');
var on = require('./on');
var bind = require('component-bind');
var debug = require('debug')('socket.io-client:socket');
var hasBin = require('has-binary');

/**
 * Module exports.
 */

module.exports = exports = Socket;

/**
 * Internal events (blacklisted).
 * These events can't be emitted by the user.
 *
 * @api private
 */

var events = {
  connect: 1,
  connect_error: 1,
  connect_timeout: 1,
  connecting: 1,
  disconnect: 1,
  error: 1,
  reconnect: 1,
  reconnect_attempt: 1,
  reconnect_failed: 1,
  reconnect_error: 1,
  reconnecting: 1,
  ping: 1,
  pong: 1
};

/**
 * Shortcut to `Emitter#emit`.
 */

var emit = Emitter.prototype.emit;

/**
 * `Socket` constructor.
 *
 * @api public
 */

function Socket (io, nsp, opts) {
  this.io = io;
  this.nsp = nsp;
  this.json = this; // compat
  this.ids = 0;
  this.acks = {};
  this.receiveBuffer = [];
  this.sendBuffer = [];
  this.connected = false;
  this.disconnected = true;
  if (opts && opts.query) {
    this.query = opts.query;
  }
  if (this.io.autoConnect) this.open();
}

/**
 * Mix in `Emitter`.
 */

Emitter(Socket.prototype);

/**
 * Subscribe to open, close and packet events
 *
 * @api private
 */

Socket.prototype.subEvents = function () {
  if (this.subs) return;

  var io = this.io;
  this.subs = [
    on(io, 'open', bind(this, 'onopen')),
    on(io, 'packet', bind(this, 'onpacket')),
    on(io, 'close', bind(this, 'onclose'))
  ];
};

/**
 * "Opens" the socket.
 *
 * @api public
 */

Socket.prototype.open =
Socket.prototype.connect = function () {
  if (this.connected) return this;

  this.subEvents();
  this.io.open(); // ensure open
  if ('open' === this.io.readyState) this.onopen();
  this.emit('connecting');
  return this;
};

/**
 * Sends a `message` event.
 *
 * @return {Socket} self
 * @api public
 */

Socket.prototype.send = function () {
  var args = toArray(arguments);
  args.unshift('message');
  this.emit.apply(this, args);
  return this;
};

/**
 * Override `emit`.
 * If the event is in `events`, it's emitted normally.
 *
 * @param {String} event name
 * @return {Socket} self
 * @api public
 */

Socket.prototype.emit = function (ev) {
  if (events.hasOwnProperty(ev)) {
    emit.apply(this, arguments);
    return this;
  }

  var args = toArray(arguments);
  var parserType = parser.EVENT; // default
  if (hasBin(args)) { parserType = parser.BINARY_EVENT; } // binary
  var packet = { type: parserType, data: args };

  packet.options = {};
  packet.options.compress = !this.flags || false !== this.flags.compress;

  // event ack callback
  if ('function' === typeof args[args.length - 1]) {
    debug('emitting packet with ack id %d', this.ids);
    this.acks[this.ids] = args.pop();
    packet.id = this.ids++;
  }

  if (this.connected) {
    this.packet(packet);
  } else {
    this.sendBuffer.push(packet);
  }

  delete this.flags;

  return this;
};

/**
 * Sends a packet.
 *
 * @param {Object} packet
 * @api private
 */

Socket.prototype.packet = function (packet) {
  packet.nsp = this.nsp;
  this.io.packet(packet);
};

/**
 * Called upon engine `open`.
 *
 * @api private
 */

Socket.prototype.onopen = function () {
  debug('transport is open - connecting');

  // write connect packet if necessary
  if ('/' !== this.nsp) {
    if (this.query) {
      this.packet({type: parser.CONNECT, query: this.query});
    } else {
      this.packet({type: parser.CONNECT});
    }
  }
};

/**
 * Called upon engine `close`.
 *
 * @param {String} reason
 * @api private
 */

Socket.prototype.onclose = function (reason) {
  debug('close (%s)', reason);
  this.connected = false;
  this.disconnected = true;
  delete this.id;
  this.emit('disconnect', reason);
};

/**
 * Called with socket packet.
 *
 * @param {Object} packet
 * @api private
 */

Socket.prototype.onpacket = function (packet) {
  if (packet.nsp !== this.nsp) return;

  switch (packet.type) {
    case parser.CONNECT:
      this.onconnect();
      break;

    case parser.EVENT:
      this.onevent(packet);
      break;

    case parser.BINARY_EVENT:
      this.onevent(packet);
      break;

    case parser.ACK:
      this.onack(packet);
      break;

    case parser.BINARY_ACK:
      this.onack(packet);
      break;

    case parser.DISCONNECT:
      this.ondisconnect();
      break;

    case parser.ERROR:
      this.emit('error', packet.data);
      break;
  }
};

/**
 * Called upon a server event.
 *
 * @param {Object} packet
 * @api private
 */

Socket.prototype.onevent = function (packet) {
  var args = packet.data || [];
  debug('emitting event %j', args);

  if (null != packet.id) {
    debug('attaching ack callback to event');
    args.push(this.ack(packet.id));
  }

  if (this.connected) {
    emit.apply(this, args);
  } else {
    this.receiveBuffer.push(args);
  }
};

/**
 * Produces an ack callback to emit with an event.
 *
 * @api private
 */

Socket.prototype.ack = function (id) {
  var self = this;
  var sent = false;
  return function () {
    // prevent double callbacks
    if (sent) return;
    sent = true;
    var args = toArray(arguments);
    debug('sending ack %j', args);

    var type = hasBin(args) ? parser.BINARY_ACK : parser.ACK;
    self.packet({
      type: type,
      id: id,
      data: args
    });
  };
};

/**
 * Called upon a server acknowlegement.
 *
 * @param {Object} packet
 * @api private
 */

Socket.prototype.onack = function (packet) {
  var ack = this.acks[packet.id];
  if ('function' === typeof ack) {
    debug('calling ack %s with %j', packet.id, packet.data);
    ack.apply(this, packet.data);
    delete this.acks[packet.id];
  } else {
    debug('bad ack %s', packet.id);
  }
};

/**
 * Called upon server connect.
 *
 * @api private
 */

Socket.prototype.onconnect = function () {
  this.connected = true;
  this.disconnected = false;
  this.emit('connect');
  this.emitBuffered();
};

/**
 * Emit buffered events (received and emitted).
 *
 * @api private
 */

Socket.prototype.emitBuffered = function () {
  var i;
  for (i = 0; i < this.receiveBuffer.length; i++) {
    emit.apply(this, this.receiveBuffer[i]);
  }
  this.receiveBuffer = [];

  for (i = 0; i < this.sendBuffer.length; i++) {
    this.packet(this.sendBuffer[i]);
  }
  this.sendBuffer = [];
};

/**
 * Called upon server disconnect.
 *
 * @api private
 */

Socket.prototype.ondisconnect = function () {
  debug('server disconnect (%s)', this.nsp);
  this.destroy();
  this.onclose('io server disconnect');
};

/**
 * Called upon forced client/server side disconnections,
 * this method ensures the manager stops tracking us and
 * that reconnections don't get triggered for this.
 *
 * @api private.
 */

Socket.prototype.destroy = function () {
  if (this.subs) {
    // clean subscriptions to avoid reconnections
    for (var i = 0; i < this.subs.length; i++) {
      this.subs[i].destroy();
    }
    this.subs = null;
  }

  this.io.destroy(this);
};

/**
 * Disconnects the socket manually.
 *
 * @return {Socket} self
 * @api public
 */

Socket.prototype.close =
Socket.prototype.disconnect = function () {
  if (this.connected) {
    debug('performing disconnect (%s)', this.nsp);
    this.packet({ type: parser.DISCONNECT });
  }

  // remove socket from pool
  this.destroy();

  if (this.connected) {
    // fire events
    this.onclose('io client disconnect');
  }
  return this;
};

/**
 * Sets the compress flag.
 *
 * @param {Boolean} if `true`, compresses the sending data
 * @return {Socket} self
 * @api public
 */

Socket.prototype.compress = function (compress) {
  this.flags = this.flags || {};
  this.flags.compress = compress;
  return this;
};