function walkFolder(currentDirPath, callback) {
  fs.readdirSync(currentDirPath).forEach(name => {
    // Skip dot files
    if (name.indexOf('.') === 0) return;

    var filePath = path.join(currentDirPath, name);
    var stat = fs.statSync(filePath);

    if (stat.isFile()) {
      callback(filePath, stat);
    } else if (stat.isDirectory()) {
      walkFolder(filePath, callback);
    }
  });
}
Override things of the default create-react-app configuration here

This is using react-app-rewired by @timarney