How to use the screenfull.onChangeHandler function in screenfull

adjustComponent(initial) {
      if (isMobile()) {
        let isFullScreen = screenfull && screenfull.isFullscreen;
        if (!isFullScreen) {
          if (parseInt(getComputedStyle(this.parentNode).height) < window.innerHeight) {
            this.style.height = getComputedStyle(this.parentNode).height;
          } else this.style.height = `${window.innerHeight}px`;
        } else {
          screenfull.onChangeHandler({ target: this }); //dispatch event
        }
        if (initial) {
          this.shadowRoot.getElementById('flipBtn').style.setProperty('display', 'none', 'important');
          let remoteCamera = this.shadowRoot.getElementById('cameraRemoteBtn');
          if (remoteCamera) {
            let localCameraBtnIcon = this.shadowRoot.querySelector('#cameraLocalBtn .circle');
            if (localCameraBtnIcon) {
              localCameraBtnIcon.innerHTML = this.shadowRoot.querySelector('#cameraRemoteBtn .circle').innerHTML;
            } else this.removeChooseLabel();
            remoteCamera.parentNode.removeChild(remoteCamera);
          }
          Array.prototype.forEach.call(this.shadowRoot.querySelectorAll('.cameraLocalLabel, .browseLabel'), elem => toggleClass(elem, 'hidden'));
          Array.prototype.forEach.call(this.shadowRoot.querySelectorAll('#flipBtn, .video video'), elem => toggleClass(elem, 'flipped'));
        }
      }
      this.adjustCardPlacer(isMobile());