Front-End Developer Interview Questions for AI Training Work

I reach for Flexbox when I'm laying out items along a single axis, like a nav bar or a row of cards, and Grid when I need to control both rows and columns at once, like a dashboard layout. Using Grid for everything works but often means fighting the tool for simple one-dimensional cases.

I start from the content, letting elements wrap and resize naturally with relative units, then add breakpoints only where the layout actually breaks rather than at fixed device widths. Designing mobile-first tends to surface real constraints earlier than starting from a wide desktop layout and shrinking it.

I reserve space for the element up front using an explicit width and height or an aspect-ratio box, so the browser allocates the right space before the content arrives. Waiting for content to load before sizing its container is the most common cause of shift I see.

Bubbling propagates an event from the target element up through its ancestors, while capturing goes the other direction, from ancestors down to the target. I've had to care about it when a parent's click handler was firing before a child's, which capturing versus bubbling order explained.

I check specificity and source order first using the browser's dev tools computed styles panel, since it shows exactly which rule won and why. Most of the time the issue is a more specific selector elsewhere or a later rule overriding the one I expected.

I'd profile on an actual mid-range mobile device or a throttled emulation rather than trusting desktop performance numbers, since CPU and network constraints differ significantly. I'd look first at JavaScript execution time and unoptimized images, which are the most common mobile-specific bottlenecks.

I'd check whether a progressive enhancement approach works, where the modern feature adds a nice-to-have improvement but the layout still functions without it, rather than blocking the feature everywhere. If the feature is load-bearing for the layout, I'd add a targeted fallback just for that browser instead of downgrading the experience for everyone.

I'd start with an automated audit to catch the easy wins, like missing alt text or insufficient color contrast, then move to manual keyboard and screen reader testing for interactive components, since automated tools miss most real usability issues. I'd prioritize fixes on the highest-traffic pages first rather than trying to fix everything at once.

A design called for a custom scroll-snapping carousel with several edge-case animations that would have taken significant time to get right across browsers. I proposed a simpler version that kept the core interaction and look, and the designer agreed once they saw how close it felt in practice.

I joined a project mixing three different approaches to state management across components. Rather than rewriting everything, I picked the pattern that fit the codebase's direction best and migrated components to it incrementally as I touched them, instead of pausing feature work for a full rewrite.