比较云函数中的两个Firestore时间戳

我正在Firestore中编写更新函数,我想比较两个 Timestamp . 我试过很多种方法,但都不管用。你能给我指出正确的比较方法吗 时间戳 在firestore。

exports.updateFunction = functions.firestore
    .document('xyz/{xyzId}')
    .onUpdate((change, context) => {
        var updatedXYZ = change.after.data();
        var oldXYZ = change.before.data();

        var newTimestamp = updatedXYZ.timing;
        var oldTimestamp = oldXYZ.timing;

        // I've tried following things but not working

        var result = newTimestamp === oldTimestamp; // not working
        var result = new Date(newTimestamp) - new Date(oldTimestamp); // not working

        return true;
    });

我想检查两个时间戳是否相同。