Function createBaseCustomElementClass

src/custom-element.js:123–2152

* Creates a base custom element class. * * @param {!Window} win The window in which to register the custom element. * @param {function(!./service/ampdoc-impl.AmpDoc, !AmpElement, ?(typeof BaseElement))} elementConnectedCallback * @return {typeof HTMLElement}

(win, elementConnectedCallback)

 * @return {typeof HTMLElement}
 */
function createBaseCustomElementClass(win, elementConnectedCallback) {
  if (win.__AMP_BASE_CE_CLASS) {
    return win.__AMP_BASE_CE_CLASS;
  }
  const htmlElement = /** @type {typeof HTMLElement} */ (win.HTMLElement);

  /**
   * @abstract @extends {HTMLElement}
   */
  class BaseCustomElement extends htmlElement {
    /** */
    constructor() {
      super();
      this.createdCallback();
    }

    /**
     * Called when elements is created. Sets instance vars since there is no
     * constructor.
     * @final
     */
    createdCallback() {
      // Flag "notbuilt" is removed by Resource manager when the resource is
      // considered to be built. See "setBuilt" method.
      /** @private {boolean} */
      this.built_ = false;

      /**
       * Several APIs require the element to be connected to the DOM tree, but
       * the CustomElement lifecycle APIs are async. This lead to subtle bugs
       * that require state tracking. See #12849, https://crbug.com/821195, and
       * https://bugs.webkit.org/show_bug.cgi?id=180940.
       * @private {boolean}
       */
      this.isConnected_ = false;

      /** @private {?Promise} */
      this.buildingPromise_ = null;

      /**
       * Indicates that the `mountCallback()` has been called and it hasn't
       * been reversed with an `unmountCallback()` call.
       * @private {boolean}
       */
      this.mounted_ = false;

      /** @private {?Promise} */
      this.mountPromise_ = null;

      /** @private {?AbortController} */
      this.mountAbortController_ = null;

      /** @private {!ReadyState_Enum} */
      this.readyState_ = ReadyState_Enum.UPGRADING;

      /** @type {boolean} */
      this.everAttached = false;