The first round was too long, as they asked in-depth questions about JavaScript and React.

In the second round, the interviewer posed a puzzle-like question. The only way to arrive at the answer was to write code that would be considered "bad" and not typical for a front-end developer in day-to-day work.

They should be careful about the people they choose to conduct interviews.

HTML

• Different tags in HTML
• Primitive vs. non-primitive tags
• Why need to have different tag names?
• What is <!DOCTYPE>?
• What happens if we don't use it?

JavaScript

• Currying and closures
• Using this in JS
• let, var, const
• React lifecycle
• Need for Redux?
• How Redux works
• Type in action dispatching
• Flattening an array
• Sum(1)(2)(3)()
• Event delegation
• Combining reducers
• call(), apply(), bind()
• Why Redux?
• When do you use refs vs. state?
• How to update state
• React Virtual DOM and DOM diffing
• Using encapsulation
• What is a SPA? How is it different from multipage applications, and what are its uses?

CSS

• Increment width and height 3 times without using width and height
• Flexbox
• Position properties
• Centering without margin, top: 0, right: 0, bottom: 0, left: 0

React

• Higher-Order Components (HOCs) and render props