FetchEvent

Every FastEdge application is a fetch event listener. The runtime dispatches a FetchEvent for each incoming HTTP request; your handler must call event.respondWith() synchronously with a Response (or Promise<Response>).

addEventListener('fetch', (event) => {
  event.respondWith(handleRequest(event));
});

async function handleRequest(event) {
  return new Response('hello', { status: 200 });
}

FetchEvent

Property / Method	Type	Description
request	Request	The incoming HTTP request.
client	ClientInfo	Information about the downstream client.
server	ServerInfo	Information about the FastEdge POP handling the request.
respondWith	(response: Response | PromiseLike<Response>) => void	Sends a response back to the client.
waitUntil	(promise: Promise<any>) => void	Extends the worker lifetime until the promise settles.

waitUntil — running work after the response is sent

event.respondWith keeps the worker alive until the response is fully sent. event.waitUntil extends that lifetime further: the worker continues running until every promise registered with waitUntil has settled. This lets you do logging, telemetry, or cache warming after the client has already received its response — without making the user wait for it.

addEventListener('fetch', (event) => {
  event.respondWith(handleRequest(event));
});

async function handleRequest(event) {
  // Fire-and-forget logging — runs after respondWith returns to the client.
  event.waitUntil(
    fetch('https://logging.example.com/log', {
      method: 'POST',
      body: JSON.stringify({ url: event.request.url, ip: event.client.address }),
      headers: { 'content-type': 'application/json' },
    }),
  );

  return new Response('ok', { status: 200 });
}

If a promise registered with waitUntil rejects, the worker still terminates cleanly — the rejection is logged but does not affect the response that was already sent.

ClientInfo

Available as event.client. Fields are derived from headers the FastEdge POP injects into the request — the application does not need to parse x-forwarded-for or x-real-ip itself. The geo namespace is populated lazily on first access.

Property	Type	Description
address	string	IPv4 or IPv6 address of the downstream client. Empty string if unavailable.
tlsJA3MD5	string	JA3 TLS-handshake fingerprint as MD5 hex. Empty for non-TLS or unavailable.
protocol	string	Protocol family — "https" or "http". Not the TLS version string.
geo	GeoInfo	Client geographic information. Populated lazily on first access.

GeoInfo

Available as event.client.geo.

Property	Type	Description
asn	string	Autonomous System Number of the client’s network.
latitude	number | null	Latitude in decimal degrees, or null if unavailable.
longitude	number | null	Longitude in decimal degrees, or null if unavailable.
region	string	Region or state code (subdivision).
continent	string	Continent code (e.g. "EU", "NA").
countryCode	string	ISO 3166-1 alpha-2 country code (e.g. "PT").
countryName	string	Country name (e.g. "Portugal").
city	string	City name. Empty when geo lookup did not resolve a city.

addEventListener('fetch', (event) => {
  const { address, geo } = event.client;
  console.log(`Request from ${address} in ${geo.city}, ${geo.countryCode}`);
  event.respondWith(new Response('ok', { status: 200 }));
});

ServerInfo

Available as event.server. The pop namespace is populated lazily on first access.

Property	Type	Description
address	string	Server-side IP address that received the request.
name	string	Server hostname.
pop	PopInfo	POP location information. Populated lazily on first access.

PopInfo

Available as event.server.pop. Useful for routing decisions, geographically-aware caching keys, or telling clients which POP served them.

Property	Type	Description
latitude	number | null	POP latitude in decimal degrees, or null if unavailable.
longitude	number | null	POP longitude in decimal degrees, or null if unavailable.
region	string	POP region or state code.
continent	string	POP continent code.
countryCode	string	ISO 3166-1 alpha-2 POP country code.
countryName	string	POP country name.
city	string	POP city.

addEventListener('fetch', (event) => {
  const { name, pop } = event.server;
  console.log(`Served by ${name} in ${pop.city}, ${pop.countryCode}`);
  event.respondWith(new Response('ok', { status: 200 }));
});