Q: What is prefetching in Next.js and how does next/link prefetch routes?

next/link **prefetches** the linked route's JS and (for static routes) data when the link is **visible/hovered**, so navigation feels **instant**. Prefetch can be disabled with prefetch={false} ; in **dev** it's off. It populates the client **Router Cache** ahead of time. <rect class='d-box-accent' x='20' y='52' width='130' height=

Question 1

next/font — how does it eliminate layout shift and external requests?

Accepted Answer

`next/font` self-hosts fonts at build, inlines `size-adjust` fallback metrics and subsets, removing Google Fonts requests and CLS.

Question 2

What is next/script and what are its strategy options in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 3

What changed for next/image defaults in Next.js 16?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes you have used `next/image`.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js 16.4.2 docs (the `image` reference and the version 16 guide) and the built-in defaults in `next/dist/shared/lib/image-config.js`, and, in the **Verified** section, against `curl` requests to the i

Question 4

How do you analyze and reduce bundle size in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 5

How does next/image optimize images in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 6

How does next/font work and why does it improve performance?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 7

What is prefetching in Next.js and how does next/link prefetch routes?

Accepted Answer

next/link **prefetches** the linked route's JS and (for static routes) data when the link is **visible/hovered**, so navigation feels **instant**. Prefetch can be disabled with prefetch={false}; in **dev** it's off. It populates the client **Router Cache** ahead of time.

Question 8

How does code splitting and next/dynamic work in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 9

How do you enable and evaluate the React Compiler in Next.js 16?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes you know React state and re-rendering.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js 16.4.2 docs (`reactCompiler`, `turbopackRustReactCompiler`, the version 16 guide) and, in the **Verified** section, against three builds of the same 16.4.2 lab app with render counts re

Question 10

next.config `reactCompiler` — should you enable the React Compiler?

Accepted Answer

Setting `reactCompiler: true` in `next.config.js` runs the React Compiler (Forget) at build — it auto-inserts memoization so you can remove most `useMemo`/`useCallback`.

NEXT.JSDECODED.

Easy

next/font — how does it eliminate layout shift and external requests?

Medium

What is next/script and what are its strategy options in Next.js?

What changed for next/image defaults in Next.js 16?

How do you analyze and reduce bundle size in Next.js?

How does next/image optimize images in Next.js?

How does next/font work and why does it improve performance?

What is prefetching in Next.js and how does next/link prefetch routes?

How does code splitting and next/dynamic work in Next.js?

How do you enable and evaluate the React Compiler in Next.js 16?

Hard

What are React Server Components and why does Next.js use them?

What is Partial Prerendering (PPR) in Next.js?

How does prefetching and navigation caching work in Next.js 16?