Dynamic OG images in NextJS

Introduction

Dynamic OG images let your website create custom preview pictures automatically. This helps your links look nice and unique when shared on social media.

You want each blog post to have its own special preview image.

Your product pages need images showing product details dynamically.

You want to show user-specific info in the preview image when sharing.

You want to update preview images automatically without manual design.

You want to improve click rates by making previews more attractive.

Syntax

NextJS

export async function GET(request) {
  const image = await generateImage({
    title: 'Hello World',
    subtitle: 'Dynamic OG Image',
  });
  return new Response(image, {
    headers: { 'Content-Type': 'image/png' },
  });
}

This example shows a Next.js API route that returns a generated image.

You can customize the image content by changing the parameters passed to the generator.

Examples

This example uses Next.js's ImageResponse to create a simple white background image with centered text.

NextJS

import { ImageResponse } from 'next/server';

export async function GET() {
  return new ImageResponse(
    (
      <div style={{
        backgroundColor: 'white',
        height: '100%',
        width: '100%',
        display: 'flex',
        justifyContent: 'center',
        alignItems: 'center',
        fontSize: 48,
        fontWeight: 'bold',
      }}>
        Hello, Next.js!
      </div>
    ),
    {
      width: 1200,
      height: 630,
    }
  );
}

This example reads a title from the URL query and shows it in the image with a blue background.

NextJS

import { ImageResponse } from 'next/server';

export async function GET(request) {
  const { searchParams } = new URL(request.url);
  const title = searchParams.get('title') || 'Default Title';

  return new ImageResponse(
    <div style={{
      backgroundColor: '#0070f3',
      height: '100%',
      width: '100%',
      display: 'flex',
      justifyContent: 'center',
      alignItems: 'center',
      color: 'white',
      fontSize: 64,
      fontWeight: 'bold',
    }}>
      {title}
    </div>,
    {
      width: 1200,
      height: 630,
    }
  );
}

Sample Program

This Next.js edge API route generates a dynamic OG image. It reads a title from the URL query and displays it with styled text on a dark background. The image size matches common social media preview dimensions.

NextJS

import { ImageResponse } from 'next/server';

export const runtime = 'edge';

export async function GET(request) {
  const { searchParams } = new URL(request.url);
  const title = searchParams.get('title') || 'Welcome to My Site';

  return new ImageResponse(
    (
      <div style={{
        backgroundColor: '#282c34',
        height: '100%',
        width: '100%',
        display: 'flex',
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'center',
        color: '#61dafb',
        fontSize: 64,
        fontWeight: 'bold',
        padding: '2rem',
        textAlign: 'center',
      }}>
        <div>{title}</div>
        <div style={{ fontSize: 32, marginTop: '1rem', color: '#ffffff' }}>
          Dynamic OG Image with Next.js
        </div>
      </div>
    ),
    {
      width: 1200,
      height: 630,
    }
  );
}

Important Notes

Dynamic OG images improve how your links look on social media.

Use Next.js's ImageResponse from the next/server module to create images on the fly.

Remember to set runtime = 'edge' for faster image generation.

Summary

Dynamic OG images create custom preview pictures automatically.

Next.js provides ImageResponse to build these images easily.

Use URL parameters to customize the image content dynamically.

Practice

1. What is the main purpose of dynamic OG images in Next.js?

easy

A. To create custom preview images automatically based on URL data

B. To improve server response time by caching images

C. To replace all static images with animated GIFs

D. To generate CSS styles dynamically for components

Solution

1. Step 1: Understand OG images

   OG images are preview pictures shown when sharing links on social media.

2. Step 2: Role of dynamic OG images in Next.js

   Dynamic OG images let you create these previews automatically using URL parameters, making each preview unique.

3. Final Answer:

   To create custom preview images automatically based on URL data -> Option A

4. Quick Check:

   Dynamic OG images = Custom previews [OK]

Hint: Dynamic OG images create previews from URL info [OK]

Common Mistakes:

• Thinking dynamic OG images improve server speed
• Confusing OG images with CSS or animations
• Assuming all images become GIFs automatically

2. Which Next.js import is required to create a dynamic OG image?

easy

A. import { generateImage } from 'next/api';

B. import { createImage } from 'next/image';

C. import { DynamicImage } from 'next/og';

D. import { ImageResponse } from 'next/server';

Solution

1. Step 1: Identify the correct import for OG images

   Next.js provides ImageResponse from 'next/server' to build dynamic OG images.

2. Step 2: Check other options

   Other imports like createImage, DynamicImage, or generateImage do not exist or are incorrect for this purpose.

3. Final Answer:

   import { ImageResponse } from 'next/server'; -> Option D

4. Quick Check:

   ImageResponse import = import { ImageResponse } from 'next/server'; [OK]

Hint: Use ImageResponse from next/server for OG images [OK]

Common Mistakes:

• Using imports from 'next/image' instead of 'next/server'
• Assuming 'next/og' or 'next/api' provide OG image tools
• Misspelling ImageResponse or import path

3. Given this Next.js API route code snippet for dynamic OG images, what will be the output image text if the URL query is ?title=Hello?

import { ImageResponse } from 'next/server';

export const runtime = 'edge';

export async function GET(request) {
  const { searchParams } = new URL(request.url);
  const title = searchParams.get('title') || 'Default';

  return new ImageResponse(
    (
      <div style={{
        backgroundColor: 'white',
        width: '100%',
        height: '100%',
        display: 'flex',
        justifyContent: 'center',
        alignItems: 'center',
        fontSize: 48,
        color: 'black'
      }}>
        {title}
      </div>
    ),
    { width: 1200, height: 630 }
  );
}

medium

A. An image with the text 'Default' centered

B. An image with the text 'Hello' centered

C. An image with no text displayed

D. A runtime error due to missing title parameter

Solution

1. Step 1: Extract the title from URL query

   The code gets the 'title' parameter from the URL. If missing, it defaults to 'Default'. Here, the query is '?title=Hello', so title = 'Hello'.

2. Step 2: Render the image with the title text

   The ImageResponse renders a div with the title text centered. Since title is 'Hello', the image will show 'Hello' centered.

3. Final Answer:

   An image with the text 'Hello' centered -> Option B

4. Quick Check:

   title param 'Hello' = text shown [OK]

Hint: Check URL param, fallback used only if missing [OK]

Common Mistakes:

• Assuming 'Default' shows even when title is provided
• Thinking missing text causes error
• Ignoring the URL query parameters

4. Identify the error in this Next.js dynamic OG image code snippet:

import { ImageResponse } from 'next/server';

export async function GET(request) {
  const { searchParams } = new URL(request.url);
  const name = searchParams.get('name');

  return new ImageResponse(
    (
      <div style={{ fontSize: 40 }}>
        Welcome, {name.toUpperCase()}!
      </div>
    ),
    { width: 800, height: 400 }
  );
}

medium

A. Calling toUpperCase() on null if 'name' is missing causes an error

B. ImageResponse must be imported from 'next/image' instead of 'next/server'

C. The style object cannot be used inside JSX for ImageResponse

D. The GET function must be synchronous, not async

Solution

1. Step 1: Check usage of name variable

   The code calls name.toUpperCase() without checking if name is null. If the URL has no 'name' parameter, name is null, causing a runtime error.

2. Step 2: Verify other parts

   Import from 'next/server' is correct. Style objects are allowed in JSX for ImageResponse. The GET function can be async.

3. Final Answer:

   Calling toUpperCase() on null if 'name' is missing causes an error -> Option A

4. Quick Check:

   Null check missing before toUpperCase() [OK]

Hint: Always check for null before string methods [OK]

Common Mistakes:

• Assuming name is always present
• Confusing import source for ImageResponse
• Thinking style objects are disallowed in JSX

5. You want to create a dynamic OG image in Next.js that shows a user's name and their score from URL parameters. The score should show 'N/A' if missing or zero. Which code snippet correctly implements this logic? A:

const score = searchParams.get('score') || 'N/A';
const displayScore = score === 0 ? 'N/A' : score;

B:

const score = Number(searchParams.get('score'));
const displayScore = score ?? 'N/A';

C:

const score = Number(searchParams.get('score'));
const displayScore = score > 0 ? score : 'N/A';

D:

const score = searchParams.get('score');
const displayScore = score === null || score === 0 ? 'N/A' : score;

hard

A. Option A

B. Option B

C. Option C

D. Option D

Solution

1. Step 1: Understand the requirement for score

   The score should be shown as a number if positive, otherwise 'N/A' if missing or zero.

2. Step 2: Analyze each option

   Snippet A uses string fallback and compares score === 0 but score is string, so '0' === 0 false and displays '0'.
   Snippet B converts score to number but uses ?? which only replaces null/undefined, not 0 or NaN, so displays 0 for score=0.
   Snippet C converts score to number and uses a clear check: if score > 0 show score else 'N/A'. This matches requirement perfectly.
   Snippet D compares score as string with === 0, but '0' === 0 false, so displays '0'.

3. Final Answer:

   Option C -> Option C

4. Quick Check:

   Number conversion + >0 check = Option C [OK]

Hint: Convert to number and check > 0 for score display [OK]

Common Mistakes:

• Not converting score to number before comparison
• Using nullish coalescing (??) that ignores zero
• Comparing string '0' instead of numeric zero