调用新对象而不删除画布中的旧对象

Question

我想在画布中调用新对象而不删除旧对象。做这个的最好方式是什么？

我已经通过调用新对象编写了代码，但是删除了先前的代码。关键功能是update（）。我考虑过关联数组，但是我不知道这是否是最佳方法。

const DIRECTION = {
  RIGHT: 1,
  IDLE: 0
}

let Package = {
  new: function () {
    return {
      size: 50,
      x: 0,
      y: (this.canvas.height / 2 - 50),
      speed: 3,
      Move: DIRECTION.RIGHT
    }
  }
}

let Main = {
  initialize: function () {
    this.canvas = document.querySelector('canvas');
    this.ctx = this.canvas.getContext('2d');

    this.canvas.width = 1000;
    this.canvas.height = 200;

    this.canvas.style.width = 100 + '%';
    this.canvas.style.height = 20 + 'vh';

    this.color = '#4BBFC3';

    this.legWidth = 25;
    this.legHeight = 100;

    this.package = Package.new.call(this);

    Conveyor.draw();
    Conveyor.loop();
  },

  draw: function () {
    //Clear whole Canvas.
    this.ctx.clearRect(
      0,
      0,
      this.canvas.width,
      this.canvas.height
    );

    //Draw empty Canvas.
    this.ctx.fillStyle = this.color;
    this.ctx.fillRect(
      0,
      0,
      this.canvas.width,
      this.canvas.height
    );

    //conveyor
    this.ctx.fillStyle = "white";
    this.ctx.fillRect(
      0,
      this.canvas.height / 2,
      this.canvas.width,
      this.canvas.height / 2 - 70
    );

    for (let legPosition = 0; legPosition < this.canvas.width; legPosition += 75) {
      this.ctx.fillStyle = 'white';
      this.ctx.fillRect(
        legPosition,
        this.canvas.height / 2,
        this.legWidth,
        this.legHeight
      );
    }
    //package
    this.ctx.fillStyle = 'black';
    this.ctx.fillRect(
      this.package.x,
      this.package.y,
      this.package.size,
      this.package.size
    )
  },

  update: function () {
    if (this.package.Move === DIRECTION.RIGHT) {
      this.package.x += this.package.speed;
    }

    if(this.package.x > 200) {
      this.package = Package.new.call(this);
    }
  },

  loop: function () {
    Conveyor.update();
    Conveyor.draw();

    window.requestAnimationFrame(Conveyor.loop);
  }
}

let Conveyor = Object.assign({}, Main);
Conveyor.initialize();

将调用新对象，但它将替换旧对象。

https://jsfiddle.net/wfg8xt79/2/