.eleventy.js

const { DateTime } = require("luxon");
const fs = require("fs");
const Image = require("@11ty/eleventy-img");
const pluginSyntaxHighlight = require("@11ty/eleventy-plugin-syntaxhighlight");
const pluginNavigation = require("@11ty/eleventy-navigation");
const markdownIt = require("markdown-it");

async function imageShortcode(
  src,
  alt,
  widths = [null, 400, 700],
  formats = ['webp', 'jpeg'],
  sizes = '(max-width: 700px) 100vw, 700px',
  loading = "lazy"
  ) {
  let metadata = await Image(src, {
    widths,
    formats
  });

  let imageAttributes = {
    alt,
    sizes,
    loading,
    decoding: "async",
  };

  // You bet we throw an error on missing alt in `imageAttributes` (alt="" works okay)
  return Image.generateHTML(metadata, imageAttributes);
}

module.exports = function(eleventyConfig) {
  // Copy the `img` and `css` folders to the output
  eleventyConfig.addPassthroughCopy("img");

  // Add plugins
  eleventyConfig.addPlugin(pluginSyntaxHighlight);
  eleventyConfig.addPlugin(pluginNavigation);

  // Alias `layout: article` to `layout: layouts/post.njk`
  eleventyConfig.addLayoutAlias("article", "layouts/article.njk");

  // shortcode
  eleventyConfig.addNunjucksAsyncShortcode("image", imageShortcode);

  eleventyConfig.addFilter("readableDate", dateObj => {
    return DateTime.fromJSDate(dateObj, {zone: 'utc'}).toFormat("dd LLL yyyy");
  });

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

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

  eleventyConfig.addFilter("filterTagList", filterTagList)

  // Create an array of all tags
  eleventyConfig.addCollection("tagList", function(collection) {
    let tagSet = new Set();
    collection.getAll().forEach(item => {
      (item.data.tags || []).forEach(tag => tagSet.add(tag));
    });

    return filterTagList([...tagSet]);
  });


  eleventyConfig.addFilter("bust", (url) => {
    const [urlPart, paramPart] = url.split("?");
    const params = new URLSearchParams(paramPart || "");
    params.set("v", DateTime.local().toFormat("X"));
    return `${urlPart}?${params}`;
  });

  // Customize Markdown library and settings:
  let markdownLibrary = markdownIt({
    html: true,
    breaks: true,
    linkify: true
  });

  eleventyConfig.setLibrary("md", markdownLibrary);

  // Override Browsersync defaults (used only with --serve)
  eleventyConfig.setBrowserSyncConfig({
    callbacks: {
      ready: function(err, browserSync) {
        const content_404 = fs.readFileSync('_site/404.html');

        browserSync.addMiddleware("*", (req, res) => {
          // Provides the 404 content without redirect.
          res.writeHead(404, {"Content-Type": "text/html; charset=UTF-8"});
          res.write(content_404);
          res.end();
        });
      },
    },
    ui: false,
    ghostMode: false
  });

  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",

    // -----------------------------------------------------------------
    // If your site deploys to a subdirectory, change `pathPrefix`.
    // Don’t worry about leading and trailing slashes, we normalize these.

    // If you don’t have a subdirectory, use "" or "/" (they do the same thing)
    // This is only used for link URLs (it does not affect your file structure)
    // Best paired with the `url` filter: https://www.11ty.dev/docs/filters/url/

    // You can also pass this in on the command line using `--pathprefix`

    // Optional (default is shown)
    pathPrefix: "/",
    // -----------------------------------------------------------------

    // These are all optional (defaults are shown):
    dir: {
      input: ".",
      includes: "_includes",
      data: "_data",
      output: "_site"
    }
  };
};