.eleventy.js

const moment = require("moment-timezone");
const markdownIt = require("markdown-it");
const purifycss = require("purify-css");
const htmlminifier = require("html-minifier");
const md = new markdownIt();

module.exports = function(eleventyConfig) {
  eleventyConfig.addPassthroughCopy("site/img");
  eleventyConfig.addPassthroughCopy("site/fonts");
  eleventyConfig.addPassthroughCopy("site/styles.css");
  eleventyConfig.addPassthroughCopy("site/script.js");
  eleventyConfig.addPassthroughCopy("site/sw.js");
  eleventyConfig.addPassthroughCopy("site/site.webmanifest");
  eleventyConfig.addPassthroughCopy("site/browserconfig.xml");
  eleventyConfig.addPassthroughCopy("site/_redirects");

  eleventyConfig.addNunjucksFilter("date", function(
    date,
    format = "YYYY-MM-DD"
  ) {
    return moment(date).format(format);
  });

  eleventyConfig.addNunjucksFilter("markdown", function(string) {
    return md.render(string);
  });

  eleventyConfig.addTransform("purifycss", async function(content, outputPath) {
    if (outputPath.endsWith(".html")) {
      return new Promise(resolve => {
        purifycss(
          content,
          ["build/styles.css"],
          {
            minify: true
          },
          css => {
            resolve(
              content.replace(
                '<link rel="stylesheet" href="/styles.css">',
                `<style>${css}</style>`
              )
            );
          }
        );
      });
    }

    return content;
  });

  eleventyConfig.addTransform("htmlminifier", async function(
    content,
    outputPath
  ) {
    if (outputPath.endsWith(".html")) {
      return htmlminifier.minify(content, {
        collapseWhitespace: true,
        minifyCSS: true,
        minifyJS: true,
        removeAttributeQuotes: true,
        removeComments: true,
        removeEmptyAttributes: true,
        removeRedundantAttributes: true,
        removeScriptTypeAttributes: true,
        removeStyleLinkTypeAttributes: true,
        sortAttributes: true,
        sortClassName: true
      });
    }

    return content;
  });

  return {
    templateFormats: ["njk", "md", "11ty.js"],

    pathPrefix: "/",
    markdownTemplateEngine: "liquid",
    htmlTemplateEngine: "njk",
    dataTemplateEngine: "njk",
    passthroughFileCopy: true,
    dir: {
      input: "site",
      includes: "../includes",
      data: "../data",
      output: "build"
    }
  };
};