fetch

import {fetch} from 'mikrojs/fetch'

Make HTTP requests using the familiar fetch API. Unlike the browser version, this fetch returns a Result to handle network-level failures explicitly.

Functions

fetch(input, init?)

function fetch(input: string, init?: RequestInit): Promise<Result<Response, FetchError>>

const result = await fetch('https://api.example.com/data')
if (!result.ok) {
  console.error('Fetch failed:', result.error.name)
  return
}

const response = result.value
console.log('Status:', response.status)
const data = await response.json()

Result vs Response

fetch returns a Result that represents whether the network request succeeded at all. The Response inside has its own .ok property that indicates whether the HTTP status was 2xx. You need to check both:

const result = await fetch('https://api.example.com/data')
if (!result.ok) {
  // Network error (no connection, DNS failure, etc.)
  return
}
if (!result.value.ok) {
  // HTTP error (404, 500, etc.)
  console.error('HTTP', result.value.status)
  return
}
const data = await result.value.json()

POST request

const result = await fetch('https://api.example.com/data', {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({temperature: 23.5}),
})

Request with timeout

const result = await fetch('https://api.example.com/data', {
  signal: AbortSignal.timeout(5000),
})
if (!result.ok && result.error.name === 'Aborted') {
  console.error('Request timed out')
}

On ESP32, aborting a request cancels the underlying HTTP task between read chunks and frees TLS buffers immediately.

Types

RequestInit

interface RequestInit {
  body?: string | null
  headers?: HeadersInit
  method?: string
  signal?: AbortSignal | null
}

Response

interface Response {
  readonly headers: Headers
  readonly ok: boolean // true if status is 200-299
  readonly redirected: boolean
  readonly status: number
  readonly statusText: string
  readonly url: string

  arrayBuffer(): Promise<ArrayBufferLike>
  json(): Promise<any>
  text(): Promise<string>
}

Headers

Standard Headers interface with get, set, has, append, delete, forEach, and getSetCookie.

HeadersInit

type HeadersInit = [string, string][] | Record<string, string> | Headers

Errors

FetchError

Variant	Fields	Description
TooManyPending	—	Too many concurrent requests
TaskFailed	—	Internal task failure
RequestFailed	message: string	Request failed (DNS, TLS, connection, timeout, etc.)
Aborted	message: string	Request was cancelled via AbortSignal