Extract specific child zips from zip file using node and express

extract_specific_child_zips.js

const express = require('express');
const fs = require('fs');
const extract = require('extract-zip')
const formidable = require('formidable');
const path = require('path');
const uploadDir = path.join(__dirname, '/uploads/');
const extractDir = path.join(__dirname, '/app/');
if (!fs.existsSync(uploadDir)) {
  fs.mkdirSync(uploadDir);
}
if (!fs.existsSync(extractDir)) {
  fs.mkdirSync(extractDir);
}

const server = express();

const uploadMedia = (req, res, next) => {
  const form = new formidable.IncomingForm();
  // file size limit 100MB. change according to your needs
  form.maxFileSize = 100 * 1024 * 1024;
  form.keepExtensions = true;
  form.multiples = true;
  form.uploadDir = uploadDir;

  // collect all form files and fileds and pass to its callback
  form.parse(req, (err, fields, files) => {
    // when form parsing fails throw error
    if (err) return res.status(500).json({ error: err });

    if (Object.keys(files).length === 0) return res.status(400).json({ message: "no files uploaded" });

    // Iterate all uploaded files and get their path, extension, final extraction path
    const filesInfo = Object.keys(files).map((key) => {
      const file = files[key];
      const filePath = file.path;
      const fileExt = path.extname(file.name);
      const fileName = path.basename(file.name, fileExt);

      return { filePath, fileExt, fileName };
    });

    // Check whether uploaded files are zip files
    const validFiles = filesInfo.every(({ fileExt }) => fileExt === '.zip');

    // if uploaded files are not zip files, return error
    if (!validFiles) return res.status(400).json({ message: "unsupported file type" });

    res.status(200).json({ uploaded: true });

    // iterate through each file path and extract them
    filesInfo.forEach(({ filePath, fileName }) => {
      extract(filePath, { dir: extractDir }, (err) => {
        if (!err) {
          fs.readdirSync(path.join(extractDir, fileName)).forEach((file) => {
            const filePath = path.join(extractDir, fileName, file);
            if (fs.statSync(filePath).isFile()) {
              if (path.extname(file) === '.zip') {
                extract(filePath, { dir: path.join(extractDir, fileName) }, (err) => {
                  if (err) {
                    console.error('extraction failed.');
                  } else {
                    fs.unlinkSync(filePath);
                  }
                });
              }
            }
          });
        }
      });
    });
  });

  // runs when new file detected in upload stream
  form.on('fileBegin', function (name, file) {
    // get the file base name `index.css.zip` => `index.html`
    const fileName = path.basename(file.name, path.extname(file.name));
    const fileExt = path.extname(file.name);
    // create files with timestamp to prevent overwrite same file names
    file.path = path.join(uploadDir, `${fileName}_${new Date().getTime()}${fileExt}`);
  });
}

server.post('/upload', uploadMedia);

server.listen(3000, (err) => {
  if (err) throw err;
});