function createSwPath(userOptions, outputDir, htmlFileName) {
  let swPath;
  if (typeof userOptions.workbox === 'object' && userOptions.workbox.swDest) {
    swPath = userOptions.workbox.swDest.replace(`${outputDir}/`, '');
  } else {
    swPath = './sw.js';
  }

  swPath = path.relative(path.dirname(htmlFileName), swPath);
  return swPath;
}
@param {SpaOptions} userOptions
@param {string} outputDir
@param {string} htmlFileName