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The Fetch API provides an interface for making HTTP requests and handling responses. It is the primary way workers communicate over HTTP.

​
fetch()

Make an HTTP request. 
function fetch(
  input: RequestInfo,
  init?: RequestInit
): Promise<Response>
​
input
Request | string
required
The resource to fetch. Can be a Request object or a URL string.
​
init
RequestInit
Optional configuration object:
  • method: HTTP method (GET, POST, PUT, DELETE, etc.)
  • headers: Headers object or record
  • body: Request body (string, ArrayBuffer, FormData, ReadableStream, etc.)
  • redirect: Redirect handling (follow, error, manual)
  • cf: Cloudflare-specific options
  • signal: AbortSignal for cancellation
​
Promise<Response>
Resolves to a Response object representing the HTTP response.

​
Request

Represents an HTTP request.

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Constructor

new Request(input: RequestInfo, init?: RequestInit)

​
Properties

​
method
string
HTTP method (e.g., GET, POST).
​
url
string
Full URL of the request.
​
headers
Headers
Headers object containing request headers.
​
body
ReadableStream | null
Request body as a stream, or null if no body.
​
bodyUsed
boolean
True if the body has been read.
​
redirect
string
Redirect mode: follow, error, or manual.
​
signal
AbortSignal
AbortSignal for cancelling the request.
​
cf
IncomingRequestCfProperties | undefined
Cloudflare-specific request properties (available on incoming requests).

​
Methods

​
clone()
method
Create a copy of the request.
clone(): Request
​
arrayBuffer()
method
Read the request body as an ArrayBuffer.
arrayBuffer(): Promise<ArrayBuffer>
​
bytes()
method
Read the request body as a Uint8Array.
bytes(): Promise<Uint8Array>
​
text()
method
Read the request body as a string.
text(): Promise<string>
​
json()
method
Parse the request body as JSON.
json<T = unknown>(): Promise<T>
​
formData()
method
Parse the request body as form data.
formData(): Promise<FormData>
​
blob()
method
Read the request body as a Blob.
blob(): Promise<Blob>

​
Response

Represents an HTTP response.

​
Constructor

new Response(body?: BodyInit | null, init?: ResponseInit)
​
body
BodyInit | null
Response body: string, ArrayBuffer, Blob, FormData, URLSearchParams, or ReadableStream.
​
init
ResponseInit
Optional configuration:
  • status: HTTP status code (default: 200)
  • statusText: Status message
  • headers: Headers object or record
  • cf: Cloudflare-specific options
  • webSocket: WebSocket to accept
  • encodeBody: Encoding type (auto, manual)

​
Properties

​
status
number
HTTP status code.
​
statusText
string
HTTP status message.
​
ok
boolean
True if status is in the range 200-299.
​
headers
Headers
Headers object containing response headers.
​
body
ReadableStream | null
Response body as a stream, or null if no body.
​
bodyUsed
boolean
True if the body has been read.
​
redirected
boolean
True if the response is the result of a redirect.
​
url
string
Final URL after redirects.
​
webSocket
WebSocket | null
WebSocket if this response accepted a WebSocket upgrade.

​
Methods

​
clone()
method
Create a copy of the response.
clone(): Response
​
arrayBuffer()
method
Read the response body as an ArrayBuffer.
arrayBuffer(): Promise<ArrayBuffer>
​
bytes()
method
Read the response body as a Uint8Array.
bytes(): Promise<Uint8Array>
​
text()
method
Read the response body as a string.
text(): Promise<string>
​
json()
method
Parse the response body as JSON.
json<T = unknown>(): Promise<T>
​
formData()
method
Parse the response body as form data.
formData(): Promise<FormData>
​
blob()
method
Read the response body as a Blob.
blob(): Promise<Blob>

​
Static methods

​
Response.json()
method
Create a Response with JSON body.
static json(
  data: any,
  init?: ResponseInit
): Response
​
Response.redirect()
method
Create a redirect response.
static redirect(
  url: string | URL,
  status?: number
): Response

​
Headers

Represents HTTP headers.

​
Constructor

new Headers(init?: HeadersInit)

​
Methods

​
get()
method
Get a header value.
get(name: string): string | null
​
has()
method
Check if a header exists.
has(name: string): boolean
​
set()
method
Set a header value, replacing any existing value.
set(name: string, value: string): void
​
append()
method
Append a value to a header.
append(name: string, value: string): void
​
delete()
method
Delete a header.
delete(name: string): void
​
forEach()
method
Iterate over headers.
forEach(
  callback: (value: string, name: string, parent: Headers) => void
): void
​
entries()
method
Get an iterator of [name, value] pairs.
entries(): IterableIterator<[string, string]>
​
keys()
method
Get an iterator of header names.
keys(): IterableIterator<string>
​
values()
method
Get an iterator of header values.
values(): IterableIterator<string>

​
Example

// Making a GET request
const response = await fetch('https://api.example.com/data');
const data = await response.json();

// Making a POST request
const response = await fetch('https://api.example.com/submit', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ key: 'value' }),
});

// Creating a Response
const response = new Response('Hello World', {
  status: 200,
  headers: {
    'Content-Type': 'text/plain',
  },
});

// Working with Headers
const headers = new Headers();
headers.set('Content-Type', 'application/json');
headers.append('X-Custom-Header', 'value');

// Cloning requests/responses
const request = new Request('https://example.com');
const clonedRequest = request.clone();

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