code: function matchesExtension(requestedUrl, opts) {
    var exts = !opts.ext || Array.isArray(opts.ext) ?
      opts.ext : [opts.ext];
  
    if (exts) {
      return exts.some(function(ext) {
        return requestedUrl.pathname.substr(ext.length * -1) === ext;
      });
    }
  }
docs: Returns boolean indicating whether the requestUrl ends with the configured extensions.
  
  @param requestedUrl - url requested by user
  @param opts - unless configuration
  @returns {boolean}