FetchEventLike

Kind: Class

Source: src/types.ts

FetchEventLike represents the event object handled during a fetch request. It coordinates response handling, exception pass-through behavior, and asynchronous work tied to the request lifecycle.

Methods

Properties

Diagram

mermaid
graph LR
  Handler[Fetch handler] --> Event[FetchEventLike]
  Event --> Response[respondWith()]
  Event --> Exceptions[passThroughOnException()]
  Event --> Background[waitUntil()]

Usage

ts
function handleFetch(event: FetchEventLike): void {
  event.passThroughOnException();

  event.waitUntil();

  event.respondWith();
}

AI Coding Instructions

• Pass FetchEventLike into fetch handler code instead of depending on a platform-specific event type.
• Call respondWith() when the handler should control the request response.
• Call passThroughOnException() before work that may fail when fallback request behavior is desired.
• Register request-related asynchronous work with waitUntil() so it remains associated with the event.

How it works

FetchEventLike is an exported abstract TypeScript class that describes the FetchEvent-shaped execution context used by Hono. It declares, but does not implement, four members: a read-only Request, respondWith, passThroughOnException, and waitUntil. [src/types.ts:2773-2778]

• request must be a read-only Request. [src/types.ts:2774]
• respondWith accepts either a Response or Promise<Response> and returns void. [src/types.ts:2775]
• passThroughOnException takes no arguments and returns void. [src/types.ts:2776]
• waitUntil accepts Promise<void> and returns void. [src/types.ts:2777]

Hono stores this type as one possible request execution context, alongside ExecutionContext, when constructing a Context. [src/context.ts:237-252] During request dispatch, HonoBase passes its received execution context into that Context. [src/hono-base.ts:407-428]

Context.event exposes the stored value as FetchEventLike only when the value exists and has a respondWith property. Otherwise, it throws Error('This context has no FetchEvent'). [src/context.ts:377-382] This is the visible runtime validation for access through c.event; the check does not verify the declared request, passThroughOnException, or waitUntil members. [src/context.ts:377-382]

The service-worker adapter passes its incoming event to app.fetch as the execution context and calls that event’s respondWith with the app response promise. [src/adapter/service-worker/handler.ts:25-35] Its local service-worker FetchEvent declaration has a read-only request, respondWith, and waitUntil; its respondWith also accepts PromiseLike<Response>. [src/adapter/service-worker/types.ts:1-14]

FetchEventLike contains no method bodies, validation logic, error handling, or direct side effects of its own; those depend on the concrete event object. [src/types.ts:2773-2778]