function handler(event) {
  const request = event.request;
  const uri = request.uri;
  const parts = uri.split("/");
  const lastPart = parts[parts.length - 1];
  const isAssetRequest = lastPart.includes(".");
  const isDirectoryRequest = uri.endsWith("/");
  const needsTrailingSlash = !isAssetRequest && !isDirectoryRequest;
  if (needsTrailingSlash) {
    const host = request.headers.host.value;
    const newURL = `https://${host}${request.uri}/`;
    return {
      statusCode: 302,
      statusDescription: "Found",
      headers: { location: { value: newURL } },
    };
  } else if (isDirectoryRequest) {
    return Object.assign(request, { uri: `${request.uri}/index.html` });
  }
  return request;
}