Why am I being asked this? What do they want to learn?

Passion

• What excites you about coding?
• Why do you want to code?
• How do you want to improve?

Interest

• Where do you go to find out more about coding (blogs/Hacker News/twitter) etc.?
• What's your favourite blog?
• Who do you look up to in the coding world?
• What new languages/frameworks interest you?

Opinionated (but humble)

• What is your favourite programming language?
• What do you like/dislike about Ruby/JS etc.?
• What do you think about the move towards everything being in JavaScript?
• Do you think there should be front-end/back-end or full-stack developers?
• When have you realised you've made a mistake? How did you handle it?

Understanding

• Name a design pattern - how would you use it?
• What does the Single Responsibility Principle mean?
• What is encapsulation?
• Why do we programme using TDD? What are the drawbacks?
• What do we mean by DRY?
• Why do we use MVC when building frameworks? 

Performance

• How would you optimise a system that is running slow?
• How would you identify bottlenecks in your system?
• What is an n plus 1 problem?

Deliberately tricky

• What are the most common assumptions about distributed systems?
• How would you manage dependency resolution for a page with many JavaScript dependencies?
• What do you think about type systems?

It's ok not to have all the answers

But at least show that you're trying to think through the problem

Behind every question is an opportunity to learn