eleventy.config.images.js

const path = require("path");
const eleventyImage = require("@11ty/eleventy-img");

function relativeToInputPath(inputPath, relativeFilePath) {
	let split = inputPath.split("/");
	split.pop();

	return path.resolve(split.join(path.sep), relativeFilePath);
}

function isFullUrl(url) {
	try {
		new URL(url);
		return true;
	} catch (e) {
		return false;
	}
}

module.exports = function (eleventyConfig) {
	// Eleventy Image shortcode
	// https://www.11ty.dev/docs/plugins/image/
	eleventyConfig.addAsyncShortcode(
		"image",
		async function imageShortcode(src, alt, widths, sizes) {
			// Full list of formats here: https://www.11ty.dev/docs/plugins/image/#output-formats
			// Warning: Avif can be resource-intensive so take care!
			let formats = ["avif", "webp", "auto", "jpeg"];
			let input;
			if (isFullUrl(src)) {
				input = src;
			} else {
				input = relativeToInputPath(this.page.inputPath, src);
			}

			let metadata = await eleventyImage(input, {
				widths: [1024], // Target width of 1024 pixels
				formats,
				outputDir: path.join(eleventyConfig.dir.output, "img"),
				urlPath: "/img/",
				filenameFormat: function (id, src, width, format, options) {
					// Preserve the original file name slug
					const extension = path.extname(src);
					const name = path.basename(src, extension);
					return `${name}.${format}`; // Removed width from the file name to keep the original slug
				},
			});

			// TODO loading=eager and fetchpriority=high
			let imageAttributes = {
				alt,
				sizes,
				loading: "lazy",
				decoding: "async",
			};

			return eleventyImage.generateHTML(metadata, imageAttributes);
		}
	);
};