Intercepting routes (.) in NextJS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when navigating to an intercepting route?

Consider a Next.js app with an intercepting route defined as (dashboard)/settings. What will the user see when navigating to /dashboard/settings?

NextJS

app/(dashboard)/layout.tsx
export default function DashboardLayout({ children }) {
  return (
    <div>
      <h1>Dashboard</h1>
      {children}
    </div>
  )
}

app/(dashboard)/settings/page.tsx
export default function Settings() {
  return <p>Settings Page</p>
}

A Only 'Dashboard' heading is shown, 'Settings Page' content is missing.

B Only 'Settings Page' is shown, 'Dashboard' heading is not rendered.

C The app throws a 404 error because intercepting routes are not supported.

D The page shows 'Dashboard' heading and below it 'Settings Page' content.

💡 Hint

Think about how layouts wrap their children in Next.js app router.

In Next.js, intercepting routes allow you to render nested layouts. The (dashboard) folder acts as a layout wrapping the settings page. So the output includes both the dashboard heading and the settings content.

📝 Syntax

intermediate

Identify the correct intercepting route syntax

Which of the following folder names correctly defines an intercepting route in Next.js app router?

A (admin)/users

B [admin]/users

C {admin}/users

D <admin>/users

💡 Hint

Intercepting routes use parentheses in folder names.

Next.js uses parentheses (...) to define intercepting routes. Square brackets [] are for dynamic segments, curly braces and angle brackets are invalid.

🔧 Debug

advanced

Why does this intercepting route fail to render nested content?

Given this layout code, why does the nested page content not appear? app/(main)/layout.tsx export default function MainLayout({ children }) { return

Main Layout

} app/(main)/profile/page.tsx export default function Profile() { return

Profile Page

}

A The layout does not render {children}, so nested pages have no place to appear.

B The folder name (main) is invalid for layouts.

C The profile page must be named index.tsx to render inside layout.

D Layouts cannot be used inside intercepting routes.

💡 Hint

Check what the layout returns in its JSX.

The layout component must include {children} in its returned JSX to render nested pages. Without it, nested content is not shown.

❓ state_output

advanced

What is the rendered output with parallel intercepting routes?

Consider this folder structure: app/(dashboard)/page.tsx app/(dashboard)/settings/page.tsx app/(dashboard)/(notifications)/page.tsx Navigating to /dashboard/(notifications) renders which content?

A Dashboard, settings, and notifications pages are all shown simultaneously.

B Both dashboard and notifications page content are shown, but settings page is hidden.

C Only the notifications page content is shown inside the dashboard layout.

D A 404 error occurs because parallel routes require special syntax.

💡 Hint

Parallel routes allow multiple UI sections to render at once.

Parallel intercepting routes let you show multiple UI parts simultaneously. The dashboard layout wraps the notifications page, and settings is hidden unless explicitly routed.

🧠 Conceptual

expert

What is the main benefit of using intercepting routes in Next.js?

Why would a developer choose to use intercepting routes in a Next.js app instead of traditional nested routes?

A To disable client-side navigation and force full page reloads.

B To automatically generate API routes alongside pages without extra configuration.

C To enable rendering multiple UI sections in parallel without changing the URL structure.

D To enforce strict URL patterns that prevent dynamic routing.

💡 Hint

Think about UI flexibility and URL management.

Intercepting routes allow showing multiple UI parts at once (parallel UI) while keeping URLs clean and flexible. This is useful for layouts like sidebars or modals that appear alongside main content.

Practice

1. What is the main purpose of intercepting routes in Next.js App Router?

easy

A. To force server-side rendering on every route

B. To reload the entire page on every navigation

C. To disable client-side navigation

D. To add UI parts without leaving the current page

Solution

1. Step 1: Understand intercepting routes concept

   Intercepting routes allow adding UI parts while staying on the same page, avoiding full reloads.

2. Step 2: Compare options with concept

   Options suggesting page reloads, disabling navigation, or forcing server-side rendering contradict the idea of smooth UI updates without full reloads.

3. Final Answer:

   To add UI parts without leaving the current page -> Option D

4. Quick Check:

   Intercepting routes = add UI parts without leaving page [OK]

Hint: Intercepting routes keep you on the page while adding UI [OK]

Common Mistakes:

• Thinking intercepting routes reload the whole page
• Confusing intercepting routes with disabling navigation
• Assuming intercepting routes force server rendering

2. Which folder name syntax is used to create an intercepting route in Next.js App Router?

easy

A. @modal

B. modal

C. (modal)

D. [modal]

Solution

1. Step 1: Recall folder naming for intercepting routes

   Intercepting routes use parentheses around folder names, like (modal), to mark them as intercepting.

2. Step 2: Evaluate options

   (modal) uses parentheses correctly. @modal uses @ for parallel routes, modal omits parentheses for regular routes, and [modal] uses square brackets for dynamic routes.

3. Final Answer:

   (modal) -> Option C

4. Quick Check:

   Intercepting route folder = parentheses [OK]

Hint: Intercepting routes use (folderName) syntax [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Omitting parentheses for intercepting routes
• Confusing @ folders with intercepting route folders

3. Given this folder structure in Next.js App Router:
app/(modal)/page.tsx
What happens when you navigate to a route inside (modal)?

medium

A. The modal UI appears without leaving the current page

B. The entire page reloads and shows only the modal content

C. Navigation fails with a 404 error

D. The modal opens in a new browser tab

Solution

1. Step 1: Understand intercepting route behavior

   Routes inside (modal) folders add UI parts like modals without leaving the current page.

2. Step 2: Analyze navigation effect

   Navigation triggers modal UI overlay, not a full page reload or error.

3. Final Answer:

   The modal UI appears without leaving the current page -> Option A

4. Quick Check:

   Navigation in (modal) = modal UI without reload [OK]

Hint: Routes in (modal) show UI without page reload [OK]

Common Mistakes:

• Expecting full page reload on modal route
• Thinking navigation causes errors
• Assuming modal opens in new tab

4. You wrote this intercepting route folder: app/@(sidebar)/page.tsx. Why does it cause a build error?

medium

A. Parentheses cannot be combined with @ in folder names

B. The folder name must be all lowercase

C. You need to add a layout.tsx file inside the folder

D. The file extension should be .jsx, not .tsx

Solution

1. Step 1: Check folder naming rules for intercepting routes

   Parentheses indicate intercepting routes; @ folders are separate special folders. Combining them is invalid syntax.

2. Step 2: Identify cause of build error

   Using @(sidebar) mixes two folder naming conventions, causing build failure.

3. Final Answer:

   Parentheses cannot be combined with @ in folder names -> Option A

4. Quick Check:

   Invalid folder name combining ( ) and @ causes error [OK]

Hint: Don't mix ( ) and @ in folder names [OK]

Common Mistakes:

• Thinking lowercase folder name fixes error
• Assuming missing layout.tsx causes build error
• Confusing file extension with folder naming

5. You want to show a sidebar UI on some pages without leaving the current page. Which folder structure correctly implements this intercepting route in Next.js App Router?

hard

A. app/(sidebar)/page.tsx without layout.tsx

B. app/(sidebar)/page.tsx with a layout.tsx inside (sidebar) wrapping children

C. app/@sidebar/page.tsx with page.tsx only

D. app/sidebar/page.tsx with a layout.tsx inside sidebar wrapping children

Solution

1. Step 1: Identify correct intercepting route folder

   Using parentheses (sidebar) marks it as an intercepting route folder.

2. Step 2: Confirm layout usage for UI wrapping

   Adding layout.tsx inside (sidebar) allows wrapping children with sidebar UI, enabling partial UI updates.

3. Step 3: Evaluate other options

   app/sidebar/page.tsx with a layout.tsx inside sidebar wrapping children lacks parentheses, so it's a normal route. app/@sidebar/page.tsx with page.tsx only uses @ which is for special folders, not intercepting routes. app/(sidebar)/page.tsx without layout.tsx misses layout.tsx, so sidebar UI won't wrap children properly.

4. Final Answer:

   app/(sidebar)/page.tsx with a layout.tsx inside (sidebar) wrapping children -> Option B

5. Quick Check:

   Intercepting route with layout wraps UI correctly [OK]

Hint: Use (folder) plus layout.tsx to wrap UI in intercepting routes [OK]

Common Mistakes:

• Omitting layout.tsx inside intercepting route folder
• Using normal folder instead of (folder) for intercepting route
• Confusing @ folders with intercepting route folders