Javascript Firebase TIMESTAMP 到日期和时间

Firebase TIMESTAMP to date and Time

提问by Kichu

I am using firebase for my chat application. In chat object I am adding time stamp using Firebase.ServerValue.TIMESTAMPmethod.

我正在将 firebase 用于我的聊天应用程序。在聊天对象中，我使用Firebase.ServerValue.TIMESTAMP方法添加时间戳。

I need to show the message received time in my chat application using this Time stamp .

我需要使用此时间戳在我的聊天应用程序中显示消息接收时间。

if it's current time i need to show the time only.It's have days difference i need to show the date and time or only date.

如果是当前时间，我只需要显示时间。它有天差，我需要显示日期和时间或只显示日期。

I used the following code for convert the Firebase time stamp but i not getting the actual time.

我使用以下代码转换 Firebase 时间戳，但没有得到实际时间。

var timestamp = '1452488445471';
var myDate = new Date(timestamp*1000);
var formatedTime=myDate.toJSON();

Please suggest the solution for this issue

请提出此问题的解决方案

回答by Bek

Firebase.ServerValue.TIMESTAMPis not actual timestamp it is constant that will be replaced with actual value in server if you have it set into some variable.

Firebase.ServerValue.TIMESTAMP不是实际时间戳，它是常量，如果您将其设置为某个变量，它将被服务器中的实际值替换。

mySessionRef.update({ startedAt: Firebase.ServerValue.TIMESTAMP });
mySessionRef.on('value', function(snapshot){ console.log(snapshot.val()) })
//{startedAt: 1452508763895}

if you want to get server time then you can use following code

如果你想获得服务器时间，那么你可以使用以下代码

  fb.ref("/.info/serverTimeOffset").on('value', function(offset) {
    var offsetVal = offset.val() || 0;
    var serverTime = Date.now() + offsetVal;
  });

回答by Tiago Gouvêa

In fact, it only work to me when used

事实上，它只在使用时对我有用

firebase.database.ServerValue.TIMESTAMP

With one 'database' more on namespace.

在命名空间上多了一个“数据库”。

回答by Kyle Finley

For those looking for the Firebase Firestoreequivalent. It's

对于那些正在寻找 Firebase Firestore等效项的人。它是

firebase.firestore.FieldValue.serverTimestamp()

e.g.

例如

firebase.firestore().collection("cities").add({
    createdAt: firebase.firestore.FieldValue.serverTimestamp(),
    name: "Tokyo",
    country: "Japan"
})
.then(function(docRef) {
    console.log("Document written with ID: ", docRef.id);
})
.catch(function(error) {
    console.error("Error adding document: ", error);
});

Docs

文档

回答by Dan Alboteanu

inside Firebase Functions transform the timestamp like so:

Firebase 函数内部转换时间戳，如下所示：

timestampObj.toDate()
timestampObj.toMillis().toString()

documentation here https://firebase.google.com/docs/reference/js/firebase.firestore.Timestamp

此处的文档https://firebase.google.com/docs/reference/js/firebase.firestore.Timestamp

回答by Matt

Solution for newer versions of Firebase (after Jan 2016)

较新版本 Firebase 的解决方案（2016 年 1 月之后）

The proper way to attach a timestamp to a database update is to attach a placeholder value in your request. In the example below Firebase will replace the createdAtproperty with a timestamp:

将时间戳附加到数据库更新的正确方法是在您的请求中附加一个占位符值。在下面的示例中，Firebase 将createdAt使用时间戳替换该属性：

firebaseRef = firebase.database().ref();
firebaseRef.set({
  foo: "bar", 
  createdAt: firebase.database.ServerValue.TIMESTAMP
});

According to the documentation, the value firebase.database.ServerValue.TIMESTAMPis: "A placeholder value for auto-populating the current timestamp (time since the Unix epoch, in milliseconds) by the Firebase Database servers."

根据文档，该值为firebase.database.ServerValue.TIMESTAMP：“Firebase 数据库服务器自动填充当前时间戳（自 Unix 纪元以来的时间，以毫秒为单位）的占位符值。”

回答by zemunkh

For Firestore that is the new generation of database from Google, following code will simply help you through this problem.

对于 Google 的新一代数据库 Firestore，以下代码将简单地帮助您解决此问题。

var admin    = require("firebase-admin");

var serviceAccount = require("../admin-sdk.json"); // auto-generated file from Google firebase.

admin.initializeApp({
  credential: admin.credential.cert(serviceAccount)
});
var db = admin.firestore();

console.log(admin.firestore.Timestamp.now().toDate());

回答by vineet

timestamp is an object

时间戳是一个对象

timestamp= {nanoseconds: 0,
seconds: 1562524200}

console.log(new Date(timestamp.seconds*1000))

回答by beytarovski

It is simple. Use that function to get server timestamp as milliseconds one time only:

很简单。使用该函数仅一次以毫秒为单位获取服务器时间戳：

var getServerTime = function( cb ) {
    this.db.ref( '.info/serverTimeOffset' ).once( 'value', function( snap ) {
      var offset = snap.val();

      // Get server time by milliseconds
      cb( new Date().getTime() + offset );
    });
};

Now you can use it anywhere like that:

现在你可以在任何地方使用它：

getServerTime( function( now ) {
    console.log( now );
});

---

---

Why use this way?

为什么要用这种方式？

According to latest Firebase documentation, you should convert your Firebase timestamp into milliseconds. So you can use estimatedServerTimeMsvariable below:

根据最新的 Firebase 文档，您应该将 Firebase 时间戳转换为毫秒。所以你可以使用estimatedServerTimeMs下面的变量：

var offsetRef = firebase.database().ref(".info/serverTimeOffset");
offsetRef.on("value", function(snap) {
  var offset = snap.val();
  var estimatedServerTimeMs = new Date().getTime() + offset;
});

While firebase.database.ServerValue.TIMESTAMP is much more accurate, and preferable for most read/write operations, it can occasionally be useful to estimate the client's clock skew with respect to the Firebase Realtime Database's servers. You can attach a callback to the location /.info/serverTimeOffset to obtain the value, in milliseconds, that Firebase Realtime Database clients add to the local reported time (epoch time in milliseconds) to estimate the server time. Note that this offset's accuracy can be affected by networking latency, and so is useful primarily for discovering large (> 1 second) discrepancies in clock time.

虽然 firebase.database.ServerValue.TIMESTAMP 更准确，并且更适合大多数读/写操作，但有时估计客户端相对于 Firebase 实时数据库服务器的时钟偏差会很有用。您可以将回调附加到位置 /.info/serverTimeOffset 以获取 Firebase 实时数据库客户端添加到本地报告时间（以毫秒为单位的纪元时间）以估计服务器时间的值（以毫秒为单位）。请注意，此偏移量的准确性可能会受到网络延迟的影响，因此主要用于发现时钟时间中的大（> 1 秒）差异。

https://firebase.google.com/docs/database/web/offline-capabilities

https://firebase.google.com/docs/database/web/offline-capabilities

回答by rockdaswift

Working with Firebase Firestone 18.0.1 (com.google.firebase.Timestamp)

使用 Firebase Firestone 18.0.1 (com.google.firebase.Timestamp)

val timestamp = (document.data["timestamp"] as Timestamp).toDate()

回答by Serge Seletskyy

Here is a safe method to convert a value from firebase Timestamp type to JS Date in case the value is not Timestamp the method returns it as it is

这是一种将值从 firebase Timestamp 类型转换为 JS Date 的安全方法，以防该值不是 Timestamp 该方法按原样返回它

Works for Angular 7/8/9

适用于 Angular 7/8/9

import firebase from 'firebase';
import Timestamp = firebase.firestore.Timestamp;

export function convertTimestampToDate(timestamp: Timestamp | any): Date | any {
  return timestamp instanceof Timestamp
    ? new Timestamp(timestamp.seconds, timestamp.nanoseconds).toDate()
    : timestamp;
}