There are supposedly 3 rounds. 2 technical and 1 HR round. First round is lasted 1 hour. They asked about almost all aspects of UI Development. Second round felt more or less like first round, but with some problem solving questions. It seems their selection criteria it very strict. You will have to be lucky to know the same niche little tricks as the interviewer knows. Because even though the interview went well, I didn't qualify for the next round. My suggestion is to prepare well for ES6 and any other latest JS/CSS related items.