javascript 设计模式 - 通过公共(public)方法回调

Question

我希望能够使用公共(public)方法进行回调，而不是将其作为参数传递

如

 function Car() {

    var that = this;

    this.onGearChanged = function(callback) {

       callback();
    }; 

   setTimeout(that.onGearChanged, 2000);
}

var car = new Car();
car.onGearChanged(function(){
   console.log("gear changed");

});

而不是

var onGearChanged = function(){
    console.log("gear changed")
}
var car = new Car(arg, arg, onGearChange);

我该怎么办？我应该遵循观察者模式吗？

Answer 1

我认为你需要这样的东西:

function Event(sender) {
    this._sender = sender;
    this._listeners = [];
}

Event.prototype = {
    attach: function (listener) {
        this._listeners.push(listener);
    },
    notify: function (args) {
        for (var i = 0; i < this._listeners.length; i++) {
            this._listeners[i](this._sender, args);
        }
    }
};

您的汽车类(class):

function Car(gear) {
     var self = this;

     self.Gear = gear;
     self.GearChanged = new Event(this);

     //Example method to trigger your GearChanged event. In your real code, you may have different logic
     self.changeGear = function (newGear){
         self.Gear = newGear;
         //notify all subscribers
         self.GearChanged.notify(newGear);
     }
}

订阅事件的示例代码:

var car = new Car("gear");
car.GearChanged.attach(function (sender,args){
    console.log("gear changed");
    console.log("new gear value is:" + args);
});
//do some logic that may trigger gearChanged event.
car.changeGear("new Gear");

您可以附加更多事件处理程序，所有这些事件处理程序都将被调用。您还可以使用此结构轻松添加更多事件，例如:tireChanged，..。