如何将画布添加到自定义类中？

class CanvasManager {
  constructor(width, height) {
    this.canvas = document.createElement('canvas');
    this.canvas.width = width;
    this.canvas.height = height;
    this.context = this.canvas.getContext('2d');
  }

  drawRectangle(x, y, width, height, color) {
    this.context.fillStyle = color;
    this.context.fillRect(x, y, width, height);
  }

  // 其他绘制方法...

  addToDOM(elementId) {
    const container = document.getElementById(elementId);
    container.appendChild(this.canvas);
  }
}

// 创建 CanvasManager 实例
const canvasManager = new CanvasManager(400, 300);

// 在画布上绘制矩形
canvasManager.drawRectangle(50, 50, 100, 100, 'red');

// 将画布添加到自定义容器中
canvasManager.addToDOM('canvas-container');