如何向firebase.database.ServerValue.TIMESTAMP添加时间

我需要将时间添加到admin.database.ServerValue.TIMESTAMP中，然后再检索它。但是，当我尝试向添加更多时间时，ServerValue.TIMESTAMP出现错误：

getTime不是函数

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

const ten_secs = 10 * 1000; // 10 seconds
const daily_secs = 24 * 60 * 60 * 1000; // 24 hrs
const weekly_secs = 168 * 60 * 60 * 1000; // 1 week

exports.update = functions.https.onRequest((request, response) => {

    const currentTimeStamp = admin.database.ServerValue.TIMESTAMP;

    const updatedSecs = new Date(currentTimeStamp.getTime() + ten_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    const updatedDay = new Date(currentTimeStamp.getTime() + daily_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    const updatedWeek = new Date(currentTimeStamp.getTime() + weekly_secs); // should be saved in the db as milliseconds for later retrieve and calculations

    console.log("updatedSecs: " + updatedSecs + " | updatedDay: " + updatedDay + " | updatedWeek: " + updatedWeek);

    const ref = admin.database().ref('schedule').child("scheduleId_123").child("my_uid")

    ref.once('value', snapshot => {

        if (!snapshot.exists()) {

            return ref.set({ "updatedSecs": updatedSecs, "updatedDay": updatedDay, "updatedWeek": updatedWeek });

        } else {

            const retrieved_updatedSecs = snapshot.child("updatedSecs").val();
            const retrieved_updatedDay = snapshot.child("updatedDay").val();
            const retrieved_updatedWeek = snapshot.child("updatedWeek").val();

            const currentTime = Date.now();

            // do some calculations with the above values and currentTime.
        }
    });
}