if you need an id that automatically increments check auto-increment in mongoDB: https://www.mongodb.com/basics/mongodb-auto-increment

example from mongoDB docs above with Atlas:

// create collections
db.createCollection("students");
db.createCollection("counters");

// create trigger
exports = async function(changeEvent) {
    var docId = changeEvent.fullDocument._id;
    
    const countercollection = context.services.get("<ATLAS-CLUSTER>").db(changeEvent.ns.db).collection("counters");
    const studentcollection = context.services.get("<ATLAS-CLUSTER>").db(changeEvent.ns.db).collection(changeEvent.ns.coll);
    
    var counter = await countercollection.findOneAndUpdate({_id: changeEvent.ns },{ $inc: { seq_value: 1 }}, { returnNewDocument: true, upsert : true});
    var updateRes = await studentcollection.updateOne({_id : docId},{ $set : {studentId : counter.seq_value}});
    
    console.log(`Updated ${JSON.stringify(changeEvent.ns)} with counter ${counter.seq_value} result : ${JSON.stringify(updateRes)}`);
    };

// Replace <ATLAS-CLUSTER> with your cluster service name.

db.students.insert({
   "name":"Jhon Doe"
});
db.students.insert({
   "name":"David Smith"
});
db.students.insert({
    "name":"Amanda Herny"
});
// get students from atlas
db.students.find().pretty();

if you need to create a random id in node, you can use the crypto package.

Option 1:

const crypto = require("crypto");

// create id
const _id = crypto.randomBytes(16).toString("hex");
// '4a82db25ba403269c009db0129a032f3'

Option 2:

const { randomUUID } = require("crypto");

const uuid = randomUUID()  
// 'e92b8088-7fd2-40fd-ad87-2c16cbedfc94'

EDIT: regarding your comment, randomUUID() definitely generates a unique id everytime. Double check your implementation of it if it doesn't work for you. You can test uuid generation in a demo script like this:

const { randomUUID } = require("crypto");

numberOfIds = 5;

// generate five unique id's
for (let i = 0; i < numberOfIds; i++) {
  const uuid = randomUUID();
  console.log(uuid);

  // prints 5 id's
  // f0151ff5-2656-400f-b4e6-c5549324f8f9
  // a8223ae3-6259-4114-951b-8c12c3d932bf
  // 3a0404fd-6f5a-40d3-9726-c549f6d62ab4
  // 35178ac4-62d5-4654-938e-0ffac378751a
  // 458bf08f-07d2-4849-bf67-6f328ff93109
}