javascript观察者模式（发布订阅模式）

var eventuality = function (that) {
            var registry = {};
            //触发事件
            that.fire = function (event) {
                var array,
                func,
                handler,
                i,
                type = typeof event === "string" ? event :event.type;
                if(registry.hasOwnProperty(type)){
                    array = registry[type];
                    for(i = 0; i<array.length; i +=1){
                        handler = array[i];
                        func = handler.method;
                        if(typeof func === 'string'){
                            func = this[func];
                        }
                        func.apply(this,handler.parameters||[event]);
                    }
                }
                return this;
            }
            that.on = function(type,method,parameters){
                var handler = {
                    method:method,
                    parameters:parameters
                };
                if(registry.hasOwnProperty(type)){
                    registry[type].push(handler);
                }else{
                    registry[type] = [handler];
                }
                return this;
            }
            return that;
        };
        var objectEventTest = {
            a:1,
            b:2,
            getA:function(){
                console.log(this.a);
            },
            getB:function(){
                console.log(this.b);
            },
            showC:function(c){
                console.log(c);
            }
        }
        eventuality(objectEventTest);
        objectEventTest.on("show","getA");
        objectEventTest.on("show","getB");
        objectEventTest.on("show1","showC",["show C!!"]);
        objectEventTest.fire("show");