Javascript設計模式-發佈/訂閱模式最小化的示例

Javascript設計模式-發佈/訂閱模式最小化的示例

示例代碼

/*經典的發佈/訂閱模式*/
var pubs = {};
(function(p){
    var events = {},
        subId = -1;

    var subscribe = p.subscribe = function(name, callback, one){
        var list = events[name] || (events[name] = []),
            token = (++subId).toString();

        list.push({
            'token' : token,
            'callback' : callback 
        });

        return token;
    }

   var publish = p.publish = function(name, data){
        var list = events[name], func;
        if(list){
            // Copy callback lists to prevent modification
            list = list.slice()

            // Execute event callbacks
            while((func = list.shift()) && func.callback){
                func.callback(name, data);
            }
        } 
    }

    // Remove event. If `callback` is undefined, remove all callbacks for the
    // event. If `event` and `callback` are both undefined, remove all callbacks
    // for all events
   var unsubscribe = p.unsubscribe = function(name, callback){
        if (!(name || callback)) {
            events = {};
            return p;
        }

        var list = events[name];

        if(list){
            if(callback){
                for (var i = list.length - 1; i >= 0; i--) {
                    if (list[i] === callback) {
                      list.splice(i, 1);
                    }
                }
            }else{
                delete events[name];
            }
        }
    }
})(pubs);

調用代碼

     var messageLogger = function(name, data){
                console.log(new Date().getTime() + "--Loggin : " + name + ":" + data )
            };

            var subcription = pubs.subscribe('inbox/newMessage', messageLogger);

            pubs.publish('inbox/newMessage', 'Hello World');
            pubs.publish('inbox/newMessage', 'Hello, are you still there?');
            pubs.unsubscribe('inbox/newMessage');

這個模式多被用在各個框架的事件模型中，其中Backbone中使用的比較典型。