First of all the HR will contact you by phone and mail. She will give you task to complete in 3 days. After you submit the task successfully, there will be a technical round. They will ask you about Node.js, React.js, MongoDB and Express. The questions were moderate but you need to have strong foundation.
After completing the first round of interview, there will be another round of interview which will be Technical+Managerial. They will ask about various backend concepts and test your knowledge in Node.js, MongoDB and questions about your own project and all.
After this final round of interview, you'll receive call from HR to know whether you're selected or not.