Method append

packages/blockly/core/layer_manager.ts:148–158

* Appends the given element to a layer. If the layer does not exist, it is * created. * * @internal

(elem: IRenderedElement, layerNum: number)

   * @internal
   */
  append(elem: IRenderedElement, layerNum: number) {
    if (!this.layers.has(layerNum)) {
      this.createLayer(layerNum);
    }
    const childElem = elem.getSvgRoot();
    if (this.layers.get(layerNum)?.lastChild !== childElem) {
      // Only append the child if it isn't already last (to avoid re-firing
      // events like focused).
      this.layers.get(layerNum)?.appendChild(childElem);
    }
  }

  /**
   * Creates a layer and inserts it at the proper place given the layer number.