More focus on core concepts in javascript, and cover each & every fundamentals of Node.js, Express.js, React.js, MongoDB
If your basics are super clear with technical answers you are good to go
There are 4 rounds -
1. Aptitude round
2. Technical interview (more focus on core js fundamentals & MERN concepts)
3. Technical interview (Slightly challenging real world based practical ques, more focus is on optimized approaches & scalability)
4. Managerial round (Discussion on salary, work culture, future responsibilities & growth