how to update date variable every midnight in node js express server to fetch from new collection `data-${date}`

I have an express server server where I need to fetch new collection from firebase that is of formate data-${date} . How can I use node schedule (or anyother method) to accomplish this task .

Code is mainly of format

let date=new Date();

app.get("/fetch",(req,res) => {
        // fetch data from firestore db `data-${date}`
}

tldr: date variable needs to be updated every midnight

You can update date every midnight in node js express server to fetch from new collection

const express = require("express");
const admin = require("firebase-admin");
const moment = require("moment");

const app = express();

admin.initializeApp({
  credential: admin.credential.cert("path/to/serviceAccountKey.json"), // 
  Replace with the path to your service account key file
});

const db = admin.firestore();

const baseCollectionName = "data";

let currentDate = moment().format("YYYY-MM-DD");

const fetchData = () => {
 const collectionName = `${baseCollectionName}-${currentDate}`;

 const collectionRef = db.collection(collectionName);

// Perform your desired operations on the collection here (e.g., fetching 
data)
 // ...
};

// Function to update the currentDate variable at midnight
const updateDateAtMidnight = () => {
 const nextMidnight = moment().endOf("day");
 const duration = moment.duration(nextMidnight.diff(moment()));

 const millisecondsUntilMidnight = duration.asMilliseconds();

 setTimeout(() => {
    currentDate = moment().format("YYYY-MM-DD");
    updateDateAtMidnight();
 }, millisecondsUntilMidnight);
};

updateDateAtMidnight();

app.get("/fetch", (req, res) => {
  fetchData();
});

app.listen(3000, () => {
 console.log("Server started on port 3000");
});

node scheduler like many other schedulers are based on cronJobs.

So you need to define a cronSettings

const cronSettings = '0 0 * * *'
// attach your function to the scheduler

const scheduledJob = schedule.scheduleJob(cronSettings , functionToUpdate)

You seem to use an express endpoint this is ok if you want also to trigger manually .

const functionToUpdate = (req, res){
   // doing something
}


app.get("/fetch",functionToUpdate)

hope it helps

Balint