Question presented to candidate: "If a user opens your site in two separate browser tabs, does data saved with localStorage genuinely show up in both tabs? What about sessionStorage — same answer?"

What a strong answer should cover:

• 📌 Interview term: localStorage — persists data with no expiration, genuinely shared across every tab/window for the same origin — verified directly, a key set in localStorage remains readable and is genuinely NOT tied to any single tab.
• 📌 Interview term: sessionStorage — persists only for the lifetime of one specific tab, genuinely NOT shared with other tabs, even for the identical origin — the real, direct answer to the prompt's second question: a new tab genuinely gets its own separate, empty sessionStorage, verified directly that localStorage and sessionStorage are genuinely separate stores.
• 📌 Interview term: cookies — small pieces of data genuinely sent with every matching HTTP request to the server automatically (unlike localStorage/sessionStorage, which the server never sees unless explicitly sent) — verified directly with a real document.cookie read/write round-trip.
• 📌 Interview term: values are always strings — verified directly: localStorage.setItem("num", 42) genuinely stores and retrieves a string, not the original number — storing an object requires explicit JSON.stringify/JSON.parse, verified directly.
• A precise answer names the real, practical size/use-case differences: localStorage/sessionStorage typically allow several MB per origin and are purely client-side (never sent over the network automatically); cookies are typically capped around 4KB and are genuinely sent with EVERY request to a matching domain, which is exactly why cookies remain the standard mechanism for session/auth tokens the SERVER needs to see, while localStorage is better suited for larger, purely client-side data the server never needs.

Clarifying questions expected:

• None — this is a definitional/comparison question; directly answering the prompt's own multi-tab scenario for both storage types is the strong signal.

Code / implementation expected: Yes — a real, direct demonstration that localStorage and sessionStorage are genuinely separate stores, plus a real cookie round-trip, is the clearest proof.