code: function toggleFullscreen(element, callback) {
      if (callback && typeof callback === 'function') {
          if (!isFullscreen()) {
              var fn = function (e) {
                  if (isFullscreen()) {
                      callback(true);
                  }
                  else {
                      callback(false);
                  }
              };
              fullscreenChange(fn);
              enterFullscreen(element);
          }
          else {
              exitFullscreen();
              callback(false);
          }
          return Promise.resolve();
      }
      return new Promise(function (resolve) {
          if (!isFullscreen()) {
              enterFullscreen(element);
          }
          else {
              exitFullscreen();
          }
          resolve();
      });
      /**
       * enter fullscreen mode.
       * @param {Element} element
       */
      function enterFullscreen(element) {
          var userAgent = navigator.userAgent.toLowerCase();
          if (element.requestFullscreen) {
              element.requestFullscreen();
          }
          else if (element.msRequestFullscreen) {
              element.msRequestFullscreen();
          }
          else if (element.mozRequestFullScreen) {
              element.parentElement.mozRequestFullScreen();
          }
          else if (userAgent.indexOf('edge') != -1) {
              element.parentElement.webkitRequestFullscreen();
          }
          else if (element.webkitRequestFullscreen) {
              element.webkitRequestFullscreen();
          }
      }
      /**
       * exit fullscreen mode.
       */
      function exitFullscreen() {
          var _doument = document;
          if (document.exitFullscreen) {
              document.exitFullscreen();
          }
          else if (_doument.msExitFullscreen) {
              _doument.msExitFullscreen();
          }
          else if (_doument.mozCancelFullScreen) {
              _doument.mozCancelFullScreen();
          }
          else if (_doument.webkitExitFullscreen) {
              _doument.webkitExitFullscreen();
          }
      }
  }
docs: switch target DOMElement to fullscreen mode.
  @param element {Element} DOMElement that you want to make fullscreen.