Skip to content

FetchHttpClient

Fetch-based implementation of the Effect HTTP client service.

This module provides an HttpClient layer that executes requests through a Web Fetch API implementation. It is the transport to use in browsers, edge runtimes, and Node.js environments where globalThis.fetch is available, or anywhere a compatible fetch function can be supplied.

3 exports Added in v4.0.0 Source

Layers

layer

Added in v4.0.0 Source

Layer that provides an HttpClient implementation backed by the configured Fetch function.

When to use

Use when an Effect program should execute HttpClient requests through the platform fetch implementation, especially in browser, edge, or Node.js runtimes with globalThis.fetch.

Details

The layer uses the current Fetch reference and optional RequestInit service for each request. Request-specific method, headers, body, and abort signal are supplied by the client and override matching RequestInit fields.

Gotchas

Fetch behavior comes from the runtime's implementation, so CORS, cookies, redirects, abort handling, and streaming support can vary by platform. Stream request bodies are sent as Web streams with duplex: "half", and any content-length header is removed before calling fetch.

See

  • Fetch for supplying the fetch implementation used by this layer
  • RequestInit for default RequestInit options applied before request-specific fields

Signature

declare const layer: Layer.Layer<HttpClient.HttpClient>;

Services

Fetch

Added in v4.0.0 Source

Context reference for the fetch implementation used by the fetch-based HTTP client.

Details

Defaults to globalThis.fetch.

Signature

declare const Fetch: Reference<(input: URL | RequestInfo, init?: RequestInit) => Promise<Response>>;

RequestInit

Added in v4.0.0 Source

Service that contains default fetch options for the fetch-based HTTP client.

When to use

Use to provide default credentials, cache, redirect, integrity, or other fetch options for outgoing HTTP requests.

Details

Request-specific method, headers, body, and abort signal are supplied by the client when a request is executed.

Signature

declare class RequestInit extends Shape<
  "effect/http/FetchHttpClient/RequestInit",
  RequestInit,
  this
> {
  constructor(_: never);
}