如何给所有fabricjs对象添加属性？

var CustomObject = fabric.util.createClass(fabric.Object, {
  type: 'customObject', // 设置对象类型

  initialize: function(options) {
    this.callSuper('initialize', options);
    // 在这里添加你想要的属性和默认值
    this.customProperty = 'customValue';
  },

  toObject: function() {
    return fabric.util.object.extend(this.callSuper('toObject'), {
      // 将自定义属性添加到对象的序列化表示中
      customProperty: this.customProperty
    });
  }
});

var canvas = new fabric.Canvas('canvas');

var customObj = new CustomObject({
  left: 100,
  top: 100,
  width: 200,
  height: 200,
  fill: 'red'
});

canvas.add(customObj);