Consider the following code:

const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
const url = 'mongodb://user:password@p0.mongodb.net:27017,p1.mongodb.net:27017,p2.mongodb.net:27017/mydatabase?replicaSet=project-0&authSource=admin&ssl=true';

MongoClient.connect(url, { useNewUrlParser: true }, (err, client) => {
  assert.equal(null, err);
  console.log('Connected successfully to server');
  client.close();  
});

This currently throws 

MongoError: seed list contains no mongos proxies, replicaset connections requires the parameter replicaSet to be supplied in the URI or options object, mongodb://server:port/db?replicaSet=name

However, if changing useNewUrlParser to false, it works, but shows the Deprecation warning:

(node:11481) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.

I am unable to find something wrong with the URL format.