pub/sub

events.js

var Events = (function() {
  var listen,
      trigger,
      remove,
      once,
      clientMap = {};
  
  listen = function(key, fn) {
    (clientMap[key] || (clientMap[key] = [])).push(fn);
  }
  
  trigger = function() {
    var key = Array.prototype.shift.apply(arguments);
    var clients = clientMap[key] || [];

    if (clients.length === 0) {
      return;
    }
    
    for (var i = 0; i < clients.length; i++) {
      clients[i].apply(this, arguments);
    }
    
  }
  
  remove = function(key, fn) {
    if (arguments.length === 0) {
      clientMap = {};
      return;
    }
    
    if (!fn) {
      clientMap[key] = [];
      return;
    }
    
    var clients = clientMap[key];
    
    for (var i = 0; i < clients.length; i++) {
      if (clients[i] === fn || clients[i].fn === fn) {
        clients.splice(i, 1);
        break;
      }
    }
  }
  
  once = function(key, fn) {
    function one () {
      fn.apply(this, arguments);
      this.remove(key, one);
    }
    
    one.fn = fn;
    this.listen(key, one);
  }
  
  return {
    listen: listen,
    trigger: trigger,
    once: once,
    remove: remove
  }
  
})();

function cb1(data) {
  console.log('login1:', data);
}

Events.listen('login', cb1);

Events.listen('login', function(data) {
  console.log('login2:', data);
});

Events.listen('login2', function(data) {
  console.log('login2:', data);
});

// Events.remove('login', cb1);

function cb2(data) {
  console.log('once:', data);
}

// Events.once('login', cb2);

// Events.remove('login', cb2);
Events.remove()
Events.trigger('login', {status: 'success'});
Events.trigger('login2', {status: 'success2'});