website/scripts/optimize-assets.js

import { readdirSync, statSync } from "fs";
import { join, relative } from "path";
import sharp from "sharp";
import { fileURLToPath } from "url";

const __dirname = fileURLToPath(new URL(".", import.meta.url));
const root_dir = join(__dirname, "../static");
const exceptions = ["assets/"];

/**
 * @type {{
 *     jpeg: sharp.JpegOptions,
 *     webp: sharp.WebpOptions,
 *     png: sharp.PngOptions,
 *     gif: sharp.GifOptions,
 *     avif: sharp.AvifOptions
 * }}
 */
const config = {
  jpeg: {
    quality: 100,
  },
  webp: {
    lossless: true,
  },
  png: {
    quality: 100,
  },
  gif: {
    quality: 100,
  },
  avif: {
    lossless: true,
  },
};

/** @type {sharp.ResizeOptions} */
const resize_config = {
  width: 1280,
  height: 1280,
  fit: sharp.fit.inside,
  withoutEnlargement: true,
};

function* walk_directory(dir) {
  const files = readdirSync(dir);

  for (const file of files) {
    const pathToFile = join(dir, file);
    const isDirectory = statSync(pathToFile).isDirectory();
    if (isDirectory) {
      yield* walk_directory(pathToFile);
    } else {
      yield pathToFile;
    }
  }
}

function is_image(file) {
  const extension = file.split(".").pop().toLowerCase();

  return Object.keys(config).includes(extension);
}

function get_relative_path(file) {
  return relative(root_dir, file);
}

async function main() {
  for (const file of walk_directory(join(__dirname, "../static"))) {
    const relative_path = get_relative_path(file);
    const is_animated = file.endsWith(".gif");
    if (!is_image(file)) continue;
    if (exceptions.some((exception) => relative_path.startsWith(exception)))
      continue;

    const image = sharp(file, {
      animated: is_animated,
    });
    const size_before = (await image.toBuffer()).length;
    const meta = await image.metadata();
    const buffer = await image[meta.format](config[meta.format])
      .resize(resize_config)
      .toBuffer();
    const size_after = buffer.length;

    if (size_after >= size_before) continue;

    console.log(relative_path);

    await sharp(buffer).toFile(file);
  }
}

await main();