//观察者列表
function ObserverList(){this.observerList = [];
}
ObserverList.prototype.add = function( obj ){return this.observerList.push( obj );
};
ObserverList.prototype.count = function(){return this.observerList.length;
};
ObserverList.prototype.get = function( index ){if( index > -1 && index < this.observerList.length ){return this.observerList[ index ];}
};
ObserverList.prototype.indexOf = function( obj, startIndex ){var i = startIndex;while( i < this.observerList.length ){if( this.observerList[i] === obj ){return i;}i++;}return -1;
};
ObserverList.prototype.removeAt = function( index ){this.observerList.splice( index, 1 );
};//目标
function Subject(){this.observers = new ObserverList();
}
Subject.prototype.addObserver = function( observer ){this.observers.add( observer );
};
Subject.prototype.removeObserver = function( observer ){this.observers.removeAt( this.observers.indexOf( observer, 0 ) );
};
Subject.prototype.notify = function( context ){var observerCount = this.observers.count();for(var i=0; i < observerCount; i++){this.observers.get(i).update( context );}
};//观察者
function Observer(){this.update = function(){// ...
  };
}

var pubsub = {};
(function(myObject) {// Storage for topics that can be broadcast// or listened tovar topics = {};// An topic identifiervar subUid = -1;// Publish or broadcast events of interest// with a specific topic name and arguments// such as the data to pass alongmyObject.publish = function( topic, args ) {if ( !topics[topic] ) {return false;}var subscribers = topics[topic],len = subscribers ? subscribers.length : 0;while (len--) {subscribers[len].func( topic, args );}return this;};// Subscribe to events of interest// with a specific topic name and a// callback function, to be executed// when the topic/event is observedmyObject.subscribe = function( topic, func ) {if (!topics[topic]) {topics[topic] = [];}var token = ( ++subUid ).toString();topics[topic].push({token: token,func: func});return token;};// Unsubscribe from a specific// topic, based on a tokenized reference// to the subscriptionmyObject.unsubscribe = function( token ) {for ( var m in topics ) {if ( topics[m] ) {for ( var i = 0, j = topics[m].length; i < j; i++ ) {if ( topics[m][i].token === token ) {topics[m].splice( i, 1 );return token;}}}}return this;};
}( pubsub ));