app.js

var jsforce = require('jsforce');

var conn = new jsforce.Connection({
  oauth2 : {
    // you can change loginUrl to connect to sandbox or prerelease env.
    loginUrl : 'https://test.salesforce.com',
    clientId : '3MVG9T46ZAw5GTfUAOzUzNDlh9exRS6m94PR1.o95_Q6t.qo8vFZkGOI_oAm3maz3oWLZ9K8Tdb1HTmVYev6a',
    clientSecret : 'DD7FE38C376FA2575F3BAFC9980CC879CFB10E84BD55FA72E426DFABCC509119',
    redirectUri : 'http://localhost:3000'
  }
});

conn.login('amine.benhamza@gmail.com', 'password', function(err, userInfo) {
  if (err) { return console.error(err); }
  // Now you can get the access token and instance URL information.
  // Save them to establish connection next time.
  console.log(conn.accessToken);
  console.log(conn.instanceUrl);
  // logged in user property
  console.log("User ID: " + userInfo.id);
  console.log("Org ID: " + userInfo.organizationId);
  // ...
});