Question library
Questions from real interviews. Drill any of them by voice in a couple of minutes, with an interviewer, a score and feedback.
What makes a React component re-render, and how do you avoid unnecessary re-renders?JuniorA React component re-renders too often, and the UI is lagging. How would you find the cause, and how would you fix it?Mid-levelUsers complain that the page stutters and lags when they scroll. How would you look for the cause, and what role might reflow and repaint play here?Mid-levelWhat happens in the browser between a change to the DOM or styles and pixels appearing on screen? How do you use that to keep animations and scrolling from janking?Senior