Revalidation strategies (time-based) in NextJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the page to revalidate every 10 seconds.

NextJS

export const revalidate = [1];

Drag options to blanks, or click blank then click option'

A0

Bfalse

C10

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using true or false instead of a number.

Setting revalidate to 0 disables revalidation.

Setting revalidate to 10 means Next.js will regenerate the page every 10 seconds.

2fill in blank

medium

Complete the code to export a function that fetches data and sets revalidation to 60 seconds.

NextJS

export async function generateStaticParams() {
  // fetch data here
}

export const revalidate = [1];

Drag options to blanks, or click blank then click option'

A60

B30

Cfalse

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using boolean values instead of a number.

Choosing a too small or zero value disables revalidation.

Setting revalidate to 60 means the page will update every 60 seconds.

3fill in blank

hard

Fix the error in the code to correctly set revalidation to 15 seconds.

NextJS

export const revalidate = [1];

Drag options to blanks, or click blank then click option'

A15

Bfalse

Ctrue

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the number inside quotes makes it a string, causing errors.

Using boolean values instead of a number.

The revalidate value must be a number, not a string. Remove quotes to fix it.

4fill in blank

hard

Fill both blanks to export a page component and set revalidation to 120 seconds.

NextJS

export default function Page() {
  return <h1>[1]</h1>;
}

export const revalidate = [2];

Drag options to blanks, or click blank then click option'

A"Hello World"

B60

C120

D"Welcome"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes incorrectly around numbers.

Putting wrong text inside the heading.

The component returns <h1>Hello World</h1> and revalidate is set to 120 seconds.

5fill in blank

hard

Fill all three blanks to export a page component that shows current time and revalidates every 5 seconds.

NextJS

export default function TimePage() {
  const now = new Date().toLocaleTimeString();
  return <p>[1] {now}</p>;
}

export const revalidate = [2];

export const dynamic = '[3]';

Drag options to blanks, or click blank then click option'

A"Current time:"

B5

Cfalse

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'true' for dynamic disables static generation.

Putting numbers inside quotes.

Missing the label text inside the paragraph.

The component shows "Current time:" followed by the time. revalidate is 5 seconds, and dynamic is set to 'false' to enable static generation with revalidation.

Practice

1. What does setting the revalidate property in getStaticProps do in Next.js?

easy

A. It tells Next.js to update the static page automatically after the specified seconds.

B. It disables static generation and forces server-side rendering.

C. It caches the page forever without any updates.

D. It triggers a client-side fetch to update the page content.

Solution

1. Step 1: Understand revalidate role in getStaticProps

   The revalidate property sets a time interval in seconds for Next.js to regenerate the static page in the background.

2. Step 2: Effect of setting revalidate

   After the specified time, Next.js updates the static page automatically without manual rebuilds or disabling static generation.

3. Final Answer:

   It tells Next.js to update the static page automatically after the specified seconds. -> Option A

4. Quick Check:

   Time-based revalidation = automatic page update [OK]

Hint: Remember: revalidate sets auto-update time in seconds [OK]

Common Mistakes:

• Thinking revalidate disables static generation
• Confusing revalidate with client-side fetching
• Assuming revalidate caches forever

2. Which of the following is the correct way to set a 10-second revalidation in getStaticProps?

easy

A. export async function getStaticProps() { return { props: {}, revalidate: null } }

B. export async function getStaticProps() { return { props: {}, revalidate: '10' } }

C. export async function getStaticProps() { return { props: {}, revalidate: true } }

D. export async function getStaticProps() { return { props: {}, revalidate: 10 } }

Solution

1. Step 1: Check the type of revalidate

   The revalidate value must be a number representing seconds.

2. Step 2: Validate each option's syntax

   export async function getStaticProps() { return { props: {}, revalidate: 10 } } uses a number 10 correctly. export async function getStaticProps() { return { props: {}, revalidate: '10' } } uses a string '10' which is invalid. The other options use boolean and null, which are incorrect types.

3. Final Answer:

   export async function getStaticProps() { return { props: {}, revalidate: 10 } } -> Option D

4. Quick Check:

   revalidate must be a number [OK]

Hint: Use a number for revalidate seconds, not string or boolean [OK]

Common Mistakes:

• Using string instead of number for revalidate
• Setting revalidate to true or null
• Forgetting to return revalidate inside the returned object

3. Given this code snippet in getStaticProps:

export async function getStaticProps() {
  return {
    props: { time: Date.now() },
    revalidate: 5
  }
}

What will happen if you visit the page multiple times within 3 seconds?

medium

A. The page will show the same time value for all visits within 3 seconds.

B. The page will update time on every visit regardless of time.

C. The page will throw an error because revalidate is too short.

D. The page will never update the time value.

Solution

1. Step 1: Understand revalidate timing

   The revalidate: 5 means Next.js regenerates the page at most every 5 seconds.

2. Step 2: Behavior within 3 seconds

   Visiting within 3 seconds means the cached page is served with the same time value because regeneration hasn't happened yet.

3. Final Answer:

   The page will show the same time value for all visits within 3 seconds. -> Option A

4. Quick Check:

   Revalidate interval controls update frequency [OK]

Hint: Page updates only after revalidate seconds pass [OK]

Common Mistakes:

• Expecting page to update on every visit
• Thinking revalidate causes errors if too small
• Assuming page never updates after first build

4. You set revalidate: 0 in getStaticProps. What is the problem with this code?

medium

A. It causes the page to never render.

B. It caches the page forever without updates.

C. It disables static generation and causes a build error.

D. It causes the page to regenerate on every request, similar to server-side rendering.

Solution

1. Step 1: Understand revalidate: 0 meaning

   Setting revalidate to 0 disables Incremental Static Regeneration (ISR). The page is generated at build time and cached forever without background regeneration.

2. Step 2: Effect on page behavior

   This results in no automatic updates, which is the problem if revalidation was intended, behaving like static generation without ISR.

3. Final Answer:

   It caches the page forever without updates. -> Option B

4. Quick Check:

   revalidate 0 = no ISR, cache forever [OK]

Hint: revalidate: 0 caches forever, no updates [OK]

Common Mistakes:

• Thinking revalidate: 0 regenerates on every request
• Believing it causes a build error
• Assuming it prevents the page from rendering

5. You want a page to update its static content every 60 seconds but only if the content has changed. Which Next.js feature combined with revalidate helps achieve this efficiently?

hard

A. Use getServerSideProps instead of getStaticProps.

B. Use revalidate: false to disable updates and manually rebuild.

C. Use revalidate: 60 with Incremental Static Regeneration (ISR) and conditional data fetching.

D. Set revalidate: 0 to regenerate on every request.

Solution

1. Step 1: Understand ISR with revalidate

   Incremental Static Regeneration (ISR) allows pages to update after a set time without full rebuilds.

2. Step 2: Combine with conditional data fetching

   Fetching data conditionally inside getStaticProps ensures updates only when content changes, saving resources.

3. Final Answer:

   Use revalidate: 60 with Incremental Static Regeneration (ISR) and conditional data fetching. -> Option C

4. Quick Check:

   ISR + revalidate = efficient timed updates [OK]

Hint: ISR with revalidate controls timed updates smartly [OK]

Common Mistakes:

• Using getServerSideProps which disables static caching
• Setting revalidate to false which is invalid
• Using revalidate 0 causing regen every request