README.md

Exercise 05: Use next/image for Image Optimization

Background

We can always use the good old <img /> HTML element to display images, but Next.js also provides an Image component that has some built-in performance optimizations:

• Improved Performance: Always serves correctly sized image for each device, using modern image formats.
• Visual Stability: Prevents Cumulative Layout Shift automatically.
• Faster Page Loads: Images are only loaded when they enter the viewport, with optional blur-up placeholders.
• Asset Flexibility: On-demand image resizing, even for images stored on remote servers.

Here's how we can use the Image component:

// pages/index.tsx

import Image from 'next/image'

import photo from '../public/photo.png'

const Home = () => {
  return (
    <Image src={photo} alt="Picture of Lazar" />
  )
}

export default Home

When we use static imports like in the example above, Next.js's Image component automatically sets the width, height, placeholder and blurDataURL props because it can analyze it on build-time.

If we want to load a remote image, it's up to us to provide the width and height props. Because we always want our apps to be secure, Next.js also requires us to provide the domains from which we'll load remote images from:

// next.config.js

module.exports = {
  images: {
    domains: ['example.com', 'cdnurl.com', ...]
  }
}

To improve our website performance, we can add a priority prop to the image that would be the Largest Contentful Paint (LCP) element for each page. This will tell Next.js to prioritize the loading of that image, and that will make our LCP score much better. The LCP element is usually the largest image visible in the viewport of the page. When you run next dev, you'll see a console warning if the LCP element is an without the priority property. Once you've identified which element is the LCP, you can add the priority prop like this:

// pages/index.tsx

import Image from 'next/image'

import photo from '../public/photo.png'

const Home = () => {
  return (
    <Image
      src={photo}
      alt="Picture of Lazar"
      priority
    />
  )
}

export default Home

🚀 Exercise

Add the "lazar.png" image (which is at the root of this project) to the Home page using the Image component.

⭐️ Challenge

Display a remote image from Twitter using the Image component.

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