How to use the leancloud-realtime.Event.LAST_READ_AT_UPDATE function in leancloud-realtime

$scope.$on("$destroy", () => {
      conversation.off(Event.MEMBERS_JOINED, membersJoinedHandler);
      conversation.off(Event.MEMBERS_LEFT, membersLeftHandler);
      conversation.off(Event.KICKED, kickedHandler);
      conversation.off(Event.INFO_UPDATED, infoUpdatedHandler);
      conversation.off(Event.MEMBER_INFO_UPDATED, memberInfoUpdateHandler);
      conversation.off(Event.MESSAGE, readMarker);
      conversation.off(Event.MESSAGE, messageUpdater);
      conversation.off(Event.LAST_DELIVERED_AT_UPDATE, receiptUpdateHandler);
      conversation.off(Event.LAST_READ_AT_UPDATE, receiptUpdateHandler);
      conversation.off('lastreadtimestampsupdate', receiptUpdateHandler);
      conversation.off(Event.MESSAGE_RECALL, replaceRecalledMessage);
      $scope.typingIndicator.off('change');
      document.removeEventListener("visibilitychange", handleVisibilityChange);
    });

const handleVisibilityChange = () => {
      if (!document.hidden && conversation.unreadMessagesCount) {
        conversation.read();
      }
    };

    conversation.on(Event.MEMBERS_JOINED, membersJoinedHandler);
    conversation.on(Event.MEMBERS_LEFT, membersLeftHandler);
    conversation.on(Event.KICKED, kickedHandler);
    conversation.on(Event.INFO_UPDATED, infoUpdatedHandler);
    conversation.on(Event.MEMBER_INFO_UPDATED, memberInfoUpdateHandler);
    conversation.on(Event.MESSAGE, readMarker);
    conversation.on(Event.MESSAGE, messageUpdater);
    conversation.on(Event.LAST_DELIVERED_AT_UPDATE, receiptUpdateHandler);
    conversation.on(Event.LAST_READ_AT_UPDATE, receiptUpdateHandler);
    conversation.on('lastreadtimestampsupdate', receiptUpdateHandler);
    conversation.on(Event.MESSAGE_RECALL, replaceRecalledMessage);
    document.addEventListener("visibilitychange", handleVisibilityChange);

    $scope.$on("$destroy", () => {
      conversation.off(Event.MEMBERS_JOINED, membersJoinedHandler);
      conversation.off(Event.MEMBERS_LEFT, membersLeftHandler);
      conversation.off(Event.KICKED, kickedHandler);
      conversation.off(Event.INFO_UPDATED, infoUpdatedHandler);
      conversation.off(Event.MEMBER_INFO_UPDATED, memberInfoUpdateHandler);
      conversation.off(Event.MESSAGE, readMarker);
      conversation.off(Event.MESSAGE, messageUpdater);
      conversation.off(Event.LAST_DELIVERED_AT_UPDATE, receiptUpdateHandler);
      conversation.off(Event.LAST_READ_AT_UPDATE, receiptUpdateHandler);
      conversation.off('lastreadtimestampsupdate', receiptUpdateHandler);
      conversation.off(Event.MESSAGE_RECALL, replaceRecalledMessage);