The CTO will ask you the usual questions about your background and technical experience. If you listed Node.js in your resume, then he will ask you how you structured one of your Node.js projects. (He seemed satisfied when I described the client/server separation.) If he thinks you might be a good match, then he'll tell you that he's setting up an interview with the development manager.
The second interview is via telephone. He'll ask basic questions about React. (Example: What are props?) There were no coding challenges. If you pass that round, then the CTO will e-mail you later that day to let you know if you passed. He'll set up the third-round interviews: 45 minutes with a Customer Service person and a junior engineer (cultural fit); 45 min with two higher-level engineers (technical); and 15 with the CTO to ask any final questions. For the "cultural fit" part, they just want to see if they like you. (The engineer said so himself.) They asked about my greatest weakness, whether I've dealt with customers in the past, what I do outside of work, and how I work with a team. For the second part, they asked if I had worked with any RESTful APIs. They asked me how I would explain React to a newbie. They asked about GET, POST, PUT, PATCH, and DELETE. They asked something about whether I preferred PUT or PATCH. In the third part, the CTO just thanked me for my time and asked if I had any more questions. I never heard back from them. If they don't want you, then they will "ghost" you.