eleventy.config.js

const { DateTime } = require("luxon");
const minifyXML = require("minify-xml");
const markdownItMathjax = require("markdown-it-mathjax3");
const markdownItAnchor = require("markdown-it-anchor");
const yaml = require("js-yaml");

const pluginRss = require("@11ty/eleventy-plugin-rss");
const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
const pluginBundle = require("@11ty/eleventy-plugin-bundle");
const pluginNavigation = require("@11ty/eleventy-navigation");
const { EleventyHtmlBasePlugin } = require("@11ty/eleventy");

const pluginDrafts = require("./eleventy.config.drafts.js");
const pluginImages = require("./eleventy.config.images.js");

const addTargetBlankToExternalLinks = (md) => {
  const defaultRender = md.renderer.rules.link_open || function(tokens, idx, options, env, self) {
    return self.renderToken(tokens, idx, options);
  };

  md.renderer.rules.link_open = function(tokens, idx, options, env, self) {
    const hrefIndex = tokens[idx].attrIndex('href');
    if (hrefIndex >= 0) {
      const href = tokens[idx].attrs[hrefIndex][1];
      if (href.startsWith('http://') || href.startsWith('https://')) {
        tokens[idx].attrPush(['target', '_blank']);
      }
    }
    return defaultRender(tokens, idx, options, env, self);
  };
};

module.exports = function (eleventyConfig) {
	eleventyConfig.setServerOptions({
		showAllHosts: true
	});
	// Copy the contents of the `public` folder to the output folder
	// For example, `./public/css/` ends up in `_site/css/`
	eleventyConfig.addPassthroughCopy({
		"./public/": "/",
		"./node_modules/prismjs/themes/prism-okaidia.css": "/css/prism-okaidia.css",
		"./node_modules/@11ty/is-land/is-land.js": "/is-land.js",
	});

	// Run Eleventy when these files change:
	// https://www.11ty.dev/docs/watch-serve/#add-your-own-watch-targets

	// Watch content images for the image pipeline.
	eleventyConfig.addWatchTarget("content/**/*.{svg,webp,png,jpeg}");

	// App plugins
	eleventyConfig.addPlugin(pluginDrafts);
	eleventyConfig.addPlugin(pluginImages);

	// Official plugins
	eleventyConfig.addPlugin(pluginRss);
	eleventyConfig.addPlugin(pluginSyntaxHighlight, {
		preAttributes: { tabindex: 0 },
	});
	eleventyConfig.addPlugin(pluginNavigation);
	eleventyConfig.addPlugin(EleventyHtmlBasePlugin);
	eleventyConfig.addPlugin(pluginBundle);

	eleventyConfig.addDataExtension("yml", (contents) => yaml.load(contents));

	// Filters
	eleventyConfig.addFilter("readableDate", (dateObj, format, zone) => {
		// Formatting tokens for Luxon: https://moment.github.io/luxon/#/formatting?id=table-of-tokens
		return DateTime.fromJSDate(dateObj, { zone: zone || "utc" }).toFormat(
			format || "dd LLLL yyyy"
		);
	});

	eleventyConfig.addFilter("withTag", function (collection, tag) {
		if (!tag) return collection;
		const filtered = collection.filter((item) =>
			(item.data.tags ?? []).includes(tag)
		);
		return filtered;
	});

	eleventyConfig.addFilter("htmlDateString", (dateObj) => {
		// dateObj input: https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-date-string
		return DateTime.fromJSDate(dateObj, { zone: "utc" }).toISO();
	});

	eleventyConfig.addFilter("htmlDateStringShort", (dateObj) => {
		// dateObj input: https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-date-string
		return DateTime.fromJSDate(dateObj, { zone: "utc" }).toFormat("MMM yyyy");
	});

	// Get the first `n` elements of a collection.
	eleventyConfig.addFilter("head", (array, n) => {
		if (!Array.isArray(array) || array.length === 0) {
			return [];
		}
		if (n < 0) {
			return array.slice(n);
		}

		return array.slice(0, n);
	});

	// Return the smallest number argument
	eleventyConfig.addFilter("min", (...numbers) => {
		return Math.min.apply(null, numbers);
	});

	// Return all the tags used in a collection
	eleventyConfig.addFilter("getAllTags", (collection) => {
		let tagSet = new Set();
		for (let item of collection) {
			(item.data.tags || []).forEach((tag) => tagSet.add(tag));
		}
		return Array.from(tagSet);
	});

	eleventyConfig.addFilter("filterTagList", function filterTagList(tags) {
		return (tags || []).filter(
			(tag) => ["all", "nav", "post", "posts"].indexOf(tag) === -1
		);
	});

	// Customize Markdown library settings:
	eleventyConfig.amendLibrary("md", (mdLib) => {
		mdLib.use(markdownItMathjax);
		mdLib.use(markdownItAnchor, {
			permalink: markdownItAnchor.permalink.ariaHidden({
				placement: "after",
				class: "header-anchor",
				symbol: "#",
				ariaHidden: false,
			}),
			level: [1, 2, 3, 4],
			slugify: eleventyConfig.getFilter("slugify"),
		});
		mdLib.use(addTargetBlankToExternalLinks);
	});

	eleventyConfig.addTransform("htmlmin", function (content) {
		if (this.page.outputPath && this.page.outputPath.endsWith(".xml")) {
			return minifyXML.minify(content, {
				shortenNamespaces: false,
			});
		}

		return content;
	});

	// Features to make your build faster (when you need them)

	// If your passthrough copy gets heavy and cumbersome, add this line
	// to emulate the file copy on the dev server. Learn more:
	// https://www.11ty.dev/docs/copy/#emulate-passthrough-copy-during-serve

	// eleventyConfig.setServerPassthroughCopyBehavior("passthrough");

	return {
		// Control which files Eleventy will process
		// e.g.: *.md, *.njk, *.html, *.liquid
		templateFormats: ["md", "njk", "html"],

		// Pre-process *.md files with: (default: `liquid`)
		markdownTemplateEngine: "njk",

		// Pre-process *.html files with: (default: `liquid`)
		htmlTemplateEngine: "njk",

		// These are all optional:
		dir: {
			input: "content", // default: "."
			includes: "../_includes", // default: "_includes"
			data: "../_data", // default: "_data"
			output: "_site",
		},

		// -----------------------------------------------------------------
		// Optional items:
		// -----------------------------------------------------------------

		// If your site deploys to a subdirectory, change `pathPrefix`.
		// Read more: https://www.11ty.dev/docs/config/#deploy-to-a-subdirectory-with-a-path-prefix

		// When paired with the HTML <base> plugin https://www.11ty.dev/docs/plugins/html-base/
		// it will transform any absolute URLs in your HTML to include this
		// folder name and does **not** affect where things go in the output folder.
		pathPrefix: "/",
	};
};