I had a preliminary interview with the lead developer and recruiter. This interview was organised by the web development bootcamp I had recently graduated from. It lasted about 30 mins and involved your typical HR questions as well as some technical.
Following that, the second stage interview was held at their offices. I was introduced to the CTO and we spoke about my motivations for becoming a dev etc. Then I was tasked with writing some functions in JS (within a Node.js framework). I was not familiar with Node.js, but this was intended to test my ability to tackle novel problems. The lead developer helped me through it and gave good prompts when I got stuck (without holding me by the hand).