node: minify [jpg, png] images

minify-images.js

// ------------------------------------------------------------------------------
//
// ディレクトリ以下の画像、もしくは単一ファイルを一括圧縮するバッチスクリプト
//
// usage:
// $ node minify-images.js [src_path]
//
// ------------------------------------------------------------------------------

const fs = require("fs");
const imagemin = require("imagemin");
const imageminJpegtran = require("imagemin-jpegtran");
const imageminPngquant = require("imagemin-pngquant");
const path = require("path");

if (!process.argv[2]) {
  console.error('command: "node minify-images.js [src_path]"');
  process.exit(1);
}

const srcPath = process.argv[2];

/**
 * base: https://gist.github.com/victorsollozzo/4134793
 * ファイルパスを再帰的に取得
 *
 * @param {*} base
 * @param {*} extensions
 * @param {*} files
 * @param {*} result
 * @returns
 */
function recursiveFindByExtensions(base, extensions, files, result) {
  const tmpFiles = files || fs.readdirSync(base);
  let tmpResult = result || [];

  tmpFiles.forEach(function (file) {
    const newBase = path.join(base, file);
    if (fs.statSync(newBase).isDirectory()) {
      tmpResult = recursiveFindByExtensions(
        newBase,
        extensions,
        fs.readdirSync(newBase),
        tmpResult
      );
      return;
    }

    for (let i = 0; i < extensions.length; i += 1) {
      const ext = extensions[i];
      if (file.substr(-1 * (ext.length + 1)) === `.${ext}`) {
        tmpResult.push(newBase);
        return;
      }
    }
  });
  return tmpResult;
}

/**
 * promiseを直列実行
 *
 * @param {*} arr
 * @returns
 */
function execPromiseInSequence(arr) {
  return arr.reduce((chained, func) => chained.then(func), Promise.resolve());
};

/**
 * 単一ファイルを圧縮する
 *
 */
async function compressImage(srcFile) {
  const destination = path.dirname(srcFile);
  console.log("----------------------------------------------------");
  console.log(`minify: ${srcFile}`);
  await imagemin([srcFile], {
    destination,
    plugins: [
      imageminJpegtran(),
      imageminPngquant({
        quality: [0.6, 0.8],
        speed: 1,
      }),
    ],
  });
  console.log("succeeded.");
}

/**
 * 実行関数
 *
 */
async function main() {
  const isDir = fs.lstatSync(path.join(process.cwd(), srcPath)).isDirectory();

  const srcFiles = isDir
    ? recursiveFindByExtensions(path.join(process.cwd(), srcPath), [
        "png",
        "jpg",
      ])
    : [srcPath];

  await execPromiseInSequence(
    srcFiles.map((srcFile) => async () => compressImage(srcFile))
  );
}

main();