Next-Image-Export-Optimizer

Use Next.js advanced <Image/> component with the static export functionality. Optimizes all static images in an additional step after the Next.js static export.

• Reduces the image size and page load times drastically through responsive images
• Fast image transformation using sharp.js (also used by the Next.js server in production)
• Conversion of JPEG and PNG files to the modern WEBP format by default
• Serve the exported React bundle only via a CDN. No server required
• Automatic generation of tiny, blurry placeholder images
• Minimal configuration necessary
• Supports TypeScript

This library makes a few assumptions:

• All images that should be optimized are stored inside the public folder like public/images
• Currently only local images are supported for optimization

Installation

npm install next-image-export-optimizer
# Or
yarn add next-image-export-optimizer
pnpm install next-image-export-optimizer

Configure the library in your Next.js configuration file:

// next.config.js
module.exports = {
  images: {
    loader: "custom",
    imageSizes: [16, 32, 48, 64, 96, 128, 256, 384],
    deviceSizes: [640, 750, 828, 1080, 1200, 1920, 2048, 3840],
  },
  env: {
    nextImageExportOptimizer_imageFolderPath: "public/images",
    nextImageExportOptimizer_exportFolderPath: "out",
    nextImageExportOptimizer_quality: 75,
    nextImageExportOptimizer_storePicturesInWEBP: true,
    nextImageExportOptimizer_generateAndUseBlurImages: true,
  },
};

1. Add the above configuration to your next.config.js
2. Specify the folder where all the images are stored. Defaults to public/images
3. Change the export command in package.json

{
-  "export": "next build && next export",
+  "export": "next build && next export && next-image-export-optimizer"
}

4. Change the <Image /> component to the <ExportedImage /> component of this library.

   Example:

   // Old
   import Image from "next/image";
   
   <Image
     src="images/VERY_LARGE_IMAGE.jpg"
     alt="Large Image"
     layout="fill"
     objectFit="cover"
   />;
   
   // New
   import ExportedImage from "next-image-export-optimizer";
   
   <ExportedImage
     src="images/VERY_LARGE_IMAGE.jpg"
     alt="Large Image"
     layout="fill"
     objectFit="cover"
   />;

5. In the development mode, the original image will be served as the optimized images are created at build time only. In the exported, static React app, the responsive images are available as srcset and dynamically loaded by the browser

6. You can output the original, unoptimized images using the unoptimized prop. Example:

   <ExportedImage
     src="images/image.jpg"
     alt="Orginal, unoptimized image"
     layout="fill"
     objectFit="cover"
     unoptimized={true}
   />

Live example

You can see a live example of the use of this library at reactapp.dev/next-image-export-optimizer

How it works

The <ExportedImage /> component of this library wraps around the <Image /> component of Next.js. Using the custom loader feature, it generates a srcset for different resolutions of the original image. The browser can then load the correct size based on the current viewport size.

In the development mode, the <ExportedImage /> component falls back to the original image.

To get the optimized images you alter the Next.js export command from

next build && next export

to

next build && next export && next-image-export-optimizer

All images in the specified folder will be optimized and reduced versions will be created based on the requested widths.

The image transformation operation is optimized as it uses hashes to determine whether an image has already been optimized or not.