adds function to bypass certain condition of request
function bypass(req, conditions = {files: 1, api: 1}) {
  if (conditions.files) {
    // bypass all files request
    let regexp = /\w+\.\w+$/i;
    if (req.path.match(regexp)) {
      return true;
    }
  }
  if (conditions.api) {
    // bypass api request
    let regexp = /^\/api\//i;
    if (req.path.match(regexp)) {
      return true;
    }
  }
}