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下面的代码是javascript obeserver模式,但是当它执行“subject.subscribeObserver(observer1);”时,出现“无法读取未定义的属性推送”的错误,似乎是我无法访问subject.observers。为什么会发生?在subscribeObserver函数中,我保留this.observers引用,但主题实例仍然无法访问它。当我使用原型模式但不返回对象模式时,它真的让我困惑。Javascript观察者模式不能访问私有属性
var Subject = function() {
this.observers = [];
return {
subscribeObserver: function(observer) {
console.log(this);
this.observers.push(observer);
},
unsubscribeObserver: function(observer) {
var index = this.observers.indexOf(observer);
if (index > -1) {
this.observers.splice(index, 1);
}
},
notifyObserver: function(observer) {
var index = this.observers.indexOf(observer);
if (index > -1) {
this.observers[index].notify(index);
}
},
notifyAllObservers: function() {
for (var i = 0; i < this.observers.length; i++) {
this.observers[i].notify(i);
};
}
};
};
var Observer = function() {
return {
notify: function(index) {
console.log("Observer " + index + " is notified!");
}
}
}
var subject = new Subject();
var observer1 = new Observer();
var observer2 = new Observer();
var observer3 = new Observer();
var observer4 = new Observer();
subject.subscribeObserver(observer1);