Method mountInternal

src/custom-element.js:638–689

* Mounts the element by calling the `BaseElement.mountCallback` method. * * Can only be called on a upgraded element. May only be called from * scheduler.js. * * @return {!Promise} * @final * @restricted

()

     * @restricted
     */
    mountInternal() {
      if (this.mountPromise_) {
        return this.mountPromise_;
      }
      this.mountAbortController_ =
        this.mountAbortController_ || new AbortController();
      const {signal} = this.mountAbortController_;
      return (this.mountPromise_ = this.buildInternal()
        .then(() => {
          devAssert(this.R1());
          if (signal.aborted) {
            // Mounting has been canceled.
            return;
          }
          this.setReadyStateInternal(
            this.readyState_ != ReadyState_Enum.MOUNTING
              ? this.readyState_
              : this.implClass_.usesLoading(this)
                ? ReadyState_Enum.LOADING
                : ReadyState_Enum.MOUNTING
          );
          this.mounted_ = true;
          const result = this.impl_.mountCallback(signal);
          // The promise supports the V0 format for easy migration. If the
          // `mountCallback` returns a promise, the assumption is that the
          // element has finished loading when the promise completes.
          return result ? result.then(RETURN_TRUE) : false;
        })
        .then((hasLoaded) => {
          this.mountAbortController_ = null;
          if (signal.aborted) {
            throw cancellation();
          }
          this.signals_.signal(CommonSignals_Enum.MOUNTED);
          if (!this.implClass_.usesLoading(this) || hasLoaded) {
            this.setReadyStateInternal(ReadyState_Enum.COMPLETE);
          }
        })
        .catch((reason) => {
          this.mountAbortController_ = null;
          if (isCancellation(reason)) {
            this.mountPromise_ = null;
          } else {
            this.signals_.rejectSignal(
              CommonSignals_Enum.MOUNTED,
              /** @type {!Error} */ (reason)
            );
            this.setReadyStateInternal(ReadyState_Enum.ERROR, reason);
          }
          throw reason;
        }));
    }

    /**
     * Requests the element to be mounted as soon as possible.