fetch

Fetch a resource from the network, and return a promise with the response.

Signature

fetch(url: string, init?: FetchOptions): Promise<FetchResponse>

Parameters

url

The URL of the requested resource. Unlike standardized fetch, this must be a string.

init

An optional argument with the following optional parameters:

interface FetchOptions {
  method?: string
  headers?: {[name: string]: string}
  body?: Uint8Array | string
  credentials?: string
  cache?: string
  redirect?: string
  referrer?: string
  integrity?: string
}

• method: The request method, e.g. GET, POST, etc.
• headers: The headers to add to the request. Note that unlike the standardized fetch, this can only be a plain javascript object.
• body: The body to add to this request, if any. This can be either a string or a Uint8Array.
• cache: The cache mode to use for this request. See https://developer.mozilla.org/en-US/docs/Web/API/Request/cache for available values.
• redirect: The redirect mode to use for this request: follow or error.
• referrer: The referrer for this request.
• integrity: The subresource integrity value of the request. See https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity for more information.

Calling fetch returns a FetchResponse object:

interface FetchResponse {
  headersObject: {[name: string]: string}
  ok: boolean
  redirected: boolean
  status: number
  statusText: string
  type: string
  url: string
  arrayBuffer(): Promise<ArrayBuffer>
  text(): Promise<string>
  json(): Promise<any>
}

• headersObject: The headers associated with the response. Note that unlike the standardized fetch, this is a plain object.
• ok: Whether the result was successful.
• redirected: Whether the response is the result of a redirect.
• status: The status code of the response.
• statusText: The status text corresponding to this status code.
• type: The type of response.
• url: The URL of the response.
• arrayBuffer(): Returns a promise with the contents of the response body as a ArrayBuffer.
• text(): Returns a promise with the contents of the response body as a string, decoded as utf-8.
• json(): Returns a promise with the contents of the response body as Javascript object.

Remarks

This function has similar behavior to the standardized fetch() function, with some minor differences. See the FetchOptions and FetchResponse interfaces for more information.