backbone.js - 定义一个新的骨干集合

Question

我试图扩展骨干集合，第一种方式是我在声明中做 new，第二种方式是我先声明，然后创建一个新实例。是做第一个错，有什么区别？

var AppointmentList = new Backbone.Collection.extend({
  model: Appointment
});

和

var AppointmentList = Backbone.Collection.extend({
  model: Appointment
});

var aptlist = new AppointmentList();

Answer 1

第一个会断

var Appointment = Backbone.Model.extend({
    defaults: {
        "time": "0000",
        "note": "This is an appointment"
    }
});


var AppointmentList = new Backbone.Collection.extend({

    model: Appointment

});

var aptlist = new AppointmentList();

在 Backbone.js 中，我们有

  var extend = function(protoProps, staticProps) {

    var parent = this;
    var child;


    if (protoProps && _.has(protoProps, 'constructor')) {
      child = protoProps.constructor;
    } else {
      child = function(){ return parent.apply(this, arguments); };
    }

    _.extend(child, parent, staticProps);


    var Surrogate = function(){ this.constructor = child; };

    Surrogate.prototype = parent.prototype;

    child.prototype = new Surrogate;


    if (protoProps) _.extend(child.prototype, protoProps);


    child.__super__ = parent.prototype;

    return child;

  };

如果您使用new运算符实例化 Backbone.Collection.extend，那么 thevar parent = this将引用扩展对象，但如果您不使用newthenvar parent = this将引用Backbone.Collection并且由于您只能调用.apply函数，因此代码将在此处中断：

child = function(){ return parent.apply(this, arguments); };

parent将是一个对象。Backbone.Collection是一个函数