如何在Backbone.js v0.5中构建深层嵌套模型

var ParentModel = Backbone.Model.extend({
  defaults: {
    name: '',
    child: null
  }
});

var ChildModel = Backbone.Model.extend({
  defaults: {
    age: 0
  }
});

var childModel = new ChildModel({ age: 10 });
var parentModel = new ParentModel({ name: 'John', child: childModel });

var childAge = parentModel.get('child').get('age');
console.log(childAge); // 输出：10

parentModel.listenTo(parentModel.get('child'), 'change:age', function() {
  console.log('Child age changed');
});

parentModel.get('child').set('age', 11); // 输出："Child age changed"

parentModel.get('child').destroy();
parentModel.destroy();