Part of my role at Twitter and Stripe involved interviewing front-end engineering candidates. We were given a fair amount of discretion on how we went about interviewing, and I developed a few different sets of questions that I thought would be interesting to share.

I’d like to prefix all of this with the caveat that hiring is extremely hard, and figuring out if someone is a good fit within 45 minutes is a demanding task. The problem with interviews is that everyone tries to hire themselves. Anybody that aces my interview probably thinks a lot like me, and that’s not necessarily a good thing. As it is, I’ve been pretty hit and miss in my decisions so far. However, I believe this approach to be a good start.

Ideally the candidate has a really full GitHub 'resume’, and we can just go back through their open source projects together. I usually browse their code and ask them questions about particular design decisions. If the candidate has an excellent track record, then the interview largely moves into whether they’d be a good social fit for the team. Otherwise, I move on to the coding questions. - Alex MacCaw, Interviewing a Front-End Web Developer, sourcing.io

Alex particularly focuses in on JS questions, which quickly dives into programming fundamentals.