Shallow routing concept in NextJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is shallow routing in Next.js?

Shallow routing lets you change the URL without running data fetching methods again or fully reloading the page. It updates the URL and state smoothly.

beginner

How do you enable shallow routing when using Next.js router?

You pass { shallow: true } as an option to router.push() or router.replace() to enable shallow routing.

intermediate

Why use shallow routing in a Next.js app?

It improves user experience by avoiding full page reloads and skipping data fetching, making navigation faster and smoother.

intermediate

Does shallow routing trigger getServerSideProps or getStaticProps again?

No, shallow routing does not trigger getServerSideProps or getStaticProps again. It only changes the URL and state on the client side.

beginner

Give an example of shallow routing usage in Next.js.

Example: router.push('/page?tab=2', undefined, { shallow: true }) changes the URL query without reloading the page or fetching data again.

What does shallow routing in Next.js avoid?

A Full page reload and data fetching

B Changing the URL

C Updating the browser history

D Rendering components

Shallow routing avoids full page reloads and data fetching, but still changes the URL and updates the browser history.

How do you enable shallow routing when navigating programmatically?

A router.reload()

B router.push(url, { shallow: false })

C router.push(url, undefined, { shallow: true })

D router.prefetch(url)

You enable shallow routing by passing { shallow: true } as the third argument to router.push or router.replace.

Which data fetching methods are NOT called again during shallow routing?

A getServerSideProps and getStaticProps

B useEffect hooks

C API routes

D Client-side state updates

Shallow routing does not trigger getServerSideProps or getStaticProps again, so data fetching on the server is skipped.

When is shallow routing most useful?

A When loading a new page completely

B When updating query parameters without full reload

C When prefetching data

D When refreshing the browser

Shallow routing is useful for updating URL parts like query parameters without reloading the whole page.

What happens to the browser history during shallow routing?

A It clears all entries

B It resets to the first page

C It does not change

D It updates normally with the new URL

Shallow routing updates the browser history with the new URL, so users can navigate back and forth.

Explain shallow routing in Next.js and why it improves user experience.

Think about how changing tabs on a page without reloading feels faster.

Describe how to implement shallow routing when changing query parameters in Next.js.

Look at the router methods and their options.

Practice

1. What does shallow routing in Next.js primarily do?

easy

A. Reloads the entire page to fetch new data

B. Prevents URL changes when navigating

C. Changes the URL without reloading the page or losing component state

D. Forces a full server-side render on every navigation

Solution

1. Step 1: Understand shallow routing purpose

   Shallow routing updates the URL but keeps the current page component and state intact without a full reload.

2. Step 2: Compare options with shallow routing behavior

   Only Changes the URL without reloading the page or losing component state describes changing the URL without reloading or losing state, matching shallow routing.

3. Final Answer:

   Changes the URL without reloading the page or losing component state -> Option C

4. Quick Check:

   Shallow routing = URL change without reload [OK]

Hint: Shallow routing changes URL but keeps page state [OK]

Common Mistakes:

• Thinking shallow routing reloads the page
• Assuming shallow routing blocks URL changes
• Confusing shallow routing with full page reload

2. Which is the correct way to enable shallow routing using Next.js router's push method?

easy

A. router.push('/page?tab=1', undefined, { shallow: true })

B. router.push('/page?tab=1', { shallow: true })

C. router.push('/page?tab=1', true)

D. router.push('/page?tab=1', { reload: false })

Solution

1. Step 1: Recall router.push syntax for shallow routing

   The third argument to router.push is an options object where shallow: true enables shallow routing.

2. Step 2: Match options with correct syntax

   router.push('/page?tab=1', undefined, { shallow: true }) correctly passes { shallow: true } as the third argument; others are incorrect or incomplete.

3. Final Answer:

   router.push('/page?tab=1', undefined, { shallow: true }) -> Option A

4. Quick Check:

   Shallow routing option is third argument object [OK]

Hint: Use third argument { shallow: true } in router.push [OK]

Common Mistakes:

• Passing shallow option as second argument
• Using boolean instead of options object
• Confusing reload option with shallow

3. Given this code snippet in a Next.js page component:

const router = useRouter();

useEffect(() => {
  console.log('Query changed:', router.query.tab);
}, [router.query.tab]);

const changeTab = () => {
  router.push('/dashboard?tab=2', undefined, { shallow: true });
};

changeTab();

What will be logged to the console after changeTab() is called?

medium

A. Query changed: 2

B. Query changed: undefined

C. Nothing is logged because shallow routing blocks query updates

D. An error occurs because shallow routing cannot update query

Solution

1. Step 1: Understand effect dependency on router.query.tab

   The effect runs when router.query.tab changes, logging its value.

2. Step 2: Analyze shallow routing effect on query

   Shallow routing updates the URL and query parameters without full reload, so router.query.tab updates to '2'.

3. Final Answer:

   Query changed: 2 -> Option A

4. Quick Check:

   Shallow routing updates query and triggers effects [OK]

Hint: Shallow routing updates query, triggers effects [OK]

Common Mistakes:

• Assuming shallow routing blocks query updates
• Expecting no console output
• Thinking shallow routing causes errors

4. Consider this Next.js code snippet:

const router = useRouter();

const handleClick = () => {
  router.push('/profile?section=info', undefined, { shallow: true });
  router.push('/profile?section=details');
};

handleClick();

What is the problem with this code regarding shallow routing?

medium

A. No problem; shallow routing applies to both pushes automatically

B. Shallow routing is ignored because it must be the first push

C. Both pushes cause full reloads because shallow routing is not supported

D. The second push overrides shallow routing, causing a full reload

Solution

1. Step 1: Examine the two router.push calls

   The first call uses shallow routing, the second does not and triggers a full reload.

2. Step 2: Understand effect of second push on routing

   The second push overrides the first and causes a full page reload, negating shallow routing.

3. Final Answer:

   The second push overrides shallow routing, causing a full reload -> Option D

4. Quick Check:

   Non-shallow push cancels shallow routing [OK]

Hint: Later push without shallow cancels shallow routing [OK]

Common Mistakes:

• Assuming shallow routing applies to all pushes automatically
• Thinking shallow routing must be first push only
• Ignoring that non-shallow push triggers reload

5. You want to implement tab navigation in a Next.js page using shallow routing to update the URL query without losing component state. Which approach correctly achieves this?

hard

A. Use router.replace without shallow option to update URL and reset state

B. Use router.push with { shallow: true } when changing tabs and listen to router.query to update UI

C. Reload the page on every tab click to fetch fresh data

D. Manually manipulate window.location to change URL without Next.js router

Solution

1. Step 1: Identify shallow routing usage for tab navigation

   Using router.push with { shallow: true } updates URL query without full reload, preserving component state.

2. Step 2: Confirm UI updates from router.query changes

   Listening to router.query allows UI to react to tab changes smoothly without losing state.

3. Final Answer:

   Use router.push with { shallow: true } and listen to router.query -> Option B

4. Quick Check:

   Shallow routing + query listening = smooth tab navigation [OK]

Hint: Use router.push with shallow and watch router.query [OK]

Common Mistakes:

• Reloading page loses component state
• Using router.replace without shallow resets state
• Manipulating window.location breaks SPA behavior