Frontend interviews in 2026 cover the same ground they always have — HTML, CSS, JavaScript, React, performance — but the bar for accessibility, web vitals, and reasoning about hydration and edge rendering has gone up sharply. Junior-passing answers from 2022 will not land a senior offer today.
Synchronous code runs first. Then the microtask queue drains completely (promises, queueMicrotask), then one macrotask runs (setTimeout, I/O). Repeat. This is why a Promise.resolve().then() runs before a setTimeout(_, 0).
useMemo caches a computed value, useCallback caches a function reference, React.memo skips re-rendering a component when props are referentially equal. Most apps overuse all three — the right default is to not memoize, and add it when you have measured a problem.
Flexbox (display: flex; place-items: center). Grid (display: grid; place-items: center). Absolute positioning with transform translate(-50%, -50%). The interviewer is checking that you reach for modern layout first.
Run Lighthouse. Inspect the LCP element. Common causes: large hero image without optimization, render-blocking JS, slow TTFB, late-discovered resources. Fix priority: preload critical resources, defer non-critical JS, optimize images (WebP/AVIF, responsive srcset), and reduce server response time.
Use semantic HTML where possible (<select> if the design allows). For custom: role="listbox", aria-activedescendant, keyboard handling (arrows, Enter, Esc), focus management, and screen reader testing. Cite the WAI-ARIA Authoring Practices.
Server components run only on the server, can fetch data directly, and never ship JavaScript to the client. Client components ship JS, can use hooks and browser APIs. The boundary is the "use client" directive. Default to server; opt into client only when you need interactivity.
Build something small and modern the week before the interview — a feature with React 19, server components, or a CSS pattern you have not used. Interviewers can tell within 30 seconds whether you have shipped recently. Practice explaining what you built, not just listing tech.
