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FetchEvent

Interfacein globals@fastly/js-compute 4.0.0View source

The event type for fetch events dispatched to a Fastly Compute service.

Contains information about the incoming request, the downstream client, and the server. Use respondWith to send a response back to the client.

Properties

client

ClientInforead-onlyView source

Information about the downstream client that made the request.

server

ServerInforead-onlyView source

Information about the server which received the request.

request

Requestread-onlyView source

The downstream request that came from the client

Methods

respondWith

View source
respondWith(response: Response | PromiseLike<Response>): void

Send a response back to the client.

Note: The service will be kept alive until the response has been fully sent.

If the response contains a streaming body created by the service itself, then the service will be kept alive until the body ReadableStream has been closed or errored.

However, if the body is a stream originating in a request to a backend, i.e. if a backend response's Response.body is passed as input to the Response constructor, the service will not be kept alive until sending the body has finished.

Note: If response is a Promise, the service will be kept alive until the response has been resolved or rejected, and the Response it resolved to has been fully sent.

Note: Use FetchEvent.waitUntil to extend the service's lifetime further if necessary.

Parameters

response: Response | PromiseLike<Response>
  • Response to send back down to the client

Returns

void

sendEarlyHints

View source
sendEarlyHints(headers: HeadersInit): void

Send a 103 Early Hints response back to the client.

Must be called before respondWith.

Parameters

headers: HeadersInit

Headers to send back down to the client.

Returns

void
event.sendEarlyHints({ link: "</style.css>; rel=preload; as=style" });


event.sendEarlyHints([
  ["link", "</style.css>; rel=preload; as=style"],
  ["link", "</script.js>; rel=preload; as=script"],
]);

waitUntil

View source
waitUntil(promise: Promise<any>): void

Extend the service's lifetime to ensure asynchronous operations succeed.

By default, a service will shut down as soon as the response passed to respondWith has been sent. waitUntil can be used to ensure that the service will stay alive until additional asynchronous operations have completed, such as sending telemetry data to a separate backend after the response has been sent.

Must be initially called synchronously within the event callback, but after that it can be called multiple times.

Parameters

promise: Promise<any>

The Promise to wait for.

Returns

void
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