The example of the asynchronous recursive directory traversal

readdir_recursive.js

// The example of the asynchronous recursive directory traversal

// Copyright (c) 2021 Martin Pravda

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.

// The Software shall be used for Good, not Evil.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

/*property
    freeze, isDirectory, isFile, length, lstat, map, push, readdir, replace,
    shift
*/

import fs from "fs";

// find the ending slash at the end of the string value
const slash_rx = /\/$/g;

function readdir(callback, dir_path) {
    fs.readdir(
        dir_path,
        function (err, files) {
            if (err) {
                callback(undefined, err);
                return;
            }

            callback(files);
        }
    );
}


function lstat(callback, path) {
    fs.lstat(
        path,
        function (err, stats) {
            if (err) {
                callback(undefined, err);
                return;
            }

            callback(stats);
        }
    );
}

function readdir_recursively(callback, path) {
    path = path.replace(slash_rx, "");
    const files_queue = [path];
    const results = [];

    function walk(path) {
        if (files_queue.length === 0) {
            callback(results);
            return;
        }

        files_queue.shift();

        lstat(
            function (stats, err) {
                if (err) {
                    callback(undefined, err);
                    return;
                }

                if (stats.isFile() === true) {
                    results.push(path);
                    walk(files_queue[0]);
                }

                if (stats.isDirectory() === true) {
                    readdir(
                        function (files, err) {
                            if (err) {
                                callback(undefined, err);
                                return;
                            }

                            files = files.map(
                                function (file_name) {
                                    return path + "/" + file_name;
                                }
                            );

                            files_queue.push(...files);
                            walk(files_queue[0]);
                        },
                        path
                    );
                }
            },
            path
        );
    }

    walk(files_queue[0]);
}

export default Object.freeze(readdir_recursively);