Get webpack entries asynchronously from dirs

README.md

Convert a bunch of dirs to Webpack entries

  foo
  |- bar
  |  `- index.js
  |- qux
  `- baz
     `- index.js

  {
    entry: {
      bar: './bar/index.js',
      baz: './baz/index.js'
    }
  }

get-entries.js

/* eslint-env node */

const path = require('path');
const fs = require('fs');
const util = require('util');
const readdir = util.promisify(fs.readdir);
const fstat = util.promisify(fs.fstat);
const open = util.promisify(fs.open);

/**
 * @param {string} dir
 * @returns {Promise<boolean>}
 */
async function isDir(dir) {
    try {
        const fd = await open(dir, 'r');
        const stat = await fstat(fd);

        return stat.isDirectory();
    } catch (ex) {
        return false;
    }
}

/**
 * @param {string} file
 * @returns {Promise<boolean>}
 */
async function isFile(file) {
    try {
        const fd = await open(file, 'r');
        const stat = await fstat(fd);

        return stat.isFile();
    } catch (ex) {
        return false;
    }
}

/**
 * @param {array} dirs
 * @returns {array}
 */
function hasResult(dirs) {
    return dirs.filter((dir) => dir);
}

/**
 * @param {string}          baseDir
 * @param {function}        matcher
 * @param {string|string[]} [extraPath]
 * @returns {Function}
 */
function getCheck(baseDir, matcher, extraPath = []) {
    return function(checkedEntry) {
        return matcher(
            path.join.apply(path, [baseDir, checkedEntry].concat(extraPath))
        ).then((result) => result && checkedEntry);
    };
}

/**
 * @param {string}          baseDir
 * @param {array}           entries
 * @param {function}        matcher
 * @param {string|string[]} [extraPath]
 * @returns {Promise<string[]>}
 */
function checkAll(baseDir, entries, matcher, extraPath) {
    return Promise.all(
        entries.map(getCheck(baseDir, matcher, extraPath))
    ).then(hasResult);
}

/**
 * @param {string} baseDir
 * @param {string} indexFile
 * @param {object} hashmap
 * @param {string} dir
 * @returns {object}
 */
function toConfig(baseDir, indexFile, hashmap, dir) {
    return {
        ...hashmap,
        [dir]: path.join(baseDir, dir, indexFile)
    };
}

/**
 * @param {string} baseDir
 * @param {string} [indexFile='index.js']
 * @returns {Promise<string[]>}
 */
exports.getEntries = async function(baseDir, indexFile = 'index.js') {
    const dirContent = await readdir(baseDir);

    return checkAll(baseDir, dirContent, isDir)
        .then((dirs) => checkAll(baseDir, dirs, isFile, indexFile))
        .then((dirs) => dirs.reduce(toConfig.bind(null, baseDir, indexFile), {}));
};

webpack.config.js

/* eslint-env node */

const getEntries = require('get-entries').getEntries;

module.exports = {
    entries: async function() {
      return await getEntries(__dirname, 'main.js');
    }
};