Resize & Optimize Images With JavaScript in Node.js

Lately, I have been working with a couple of image-intensive projects with Node.js, Next.js, React.js, and really only with JavaScript. I used to use a package called gm to optimize and resize images but that came at a cost of installing a couple of other native packages like GraphicsMagick and ImageMagick for node.

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Lately, I have been working with a couple of image-intensive projects with Node.js, Next.js, React.js, and really only with JavaScript. I used to use a package called gm to optimize and resize images but that came at a cost of installing a couple of other native packages like GraphicsMagick and ImageMagick for node.

Naturally, that’s not a good thing for a project that’s being used by several developers on macOS, Windows, Linux, and on Raspberry Pi in the near future. So, in search of a better and JavaScript the only good solution I finally found a package called Jimp — which has been pretty great to work with. Props to Oliver Moran.

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Resizing & Optimizing images in Node.js

Let’s get started with Jimp and resize a set of images while also optimizing them in sort of an automated way. So, this is what you need:

images an array of images paths.
width desired width number.
height automatically resize the height as per the width while observing the same aspect ratio so that we don’t have to guess.
quality the desired quality number like e.g., 90% would do.

❯ Install Jimp

At this point, I assume that you have Node.js/npm installed and you have already kickstarted a project using npm init. Am I right?!

npm install jimp

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❯ Read, Resize, Optimize, and Write

Now that we have installed jimp, we need to use jimp to read an image path, resize it, optimize it, and finally write the new image to the same path.

	/* RESIZE OPTIMIZE IMAGES */
	const Jimp = require('jimp');

	/**
	* Resize + optimize images.
	*
	* @param Array images An array of images paths.
	* @param Number width A number value of width e.g. 1920.
	* @param Number height Optional number value of height e.g. 1080.
	* @param Number quality Optional number value of quality of the image e.g. 90.
	*/
	module.exports = async (images, width, height = Jimp.AUTO, quality) => {
	await Promise.all(
	images.map(async imgPath => {
	const image = await Jimp.read(imgPath);
	await image.resize(width, height);
	await image.quality(quality);
	await image.writeAsync(imgPath);
	})
	);
	};

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Explanation

await Jimp.read(imgPath) Reading the image.
await image.resize(width, height) Resize the image with the given width but I don’t use height so the default value of Jimp.AUTO would resize the height as per the given width but keeping the same aspect ratio. This keeps things easy, you don’t have to do the math.
await image.quality(quality) Set a certain quality like 90%.
await image.writeAsync(imgPath) Write the image without callback in an async way. Super important to not use the .write method with async/await. I’ve been down that rabbit hole.

That’s pretty much about it. Go ahead and use this function.

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Node.js Module: `resize-optimize-images`

That’s right. I have wrapped this in a nice little yet configurable node module called resize-optimize-images that you can install in your Node.js projects. This is how you go about it.

❯ Install

npm install resize-optimize-images

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❯ Usage

	const resizeOptimizeImages = require('resize-optimize-images');

	(async () => {
	// Set the options.
	const options = {
	images: ['path/to/image.jpg', 'path/to/image.png'],
	width: 1920,
	quality: 90
	};

	// Run the module.
	await resizeOptimizeImages(options);
	})();