ohmyfetch: A TypeScript repository from Grabarz & Partner Werbeagentur GmbH

🚀 Quick Start

Install:

# npm
npm i ohmyfetch

# yarn
yarn add ohmyfetch

Import:

// ESM / Typescript
import { $fetch } from 'ohmyfetch'

// CommonJS
const { $fetch } = require('ohmyfetch')

Spoiler

✔️ Works with Node.js

We use conditional exports to detect Node.js and automatically use node-fetch. If globalThis.fetch is available, will be used instead. To leverage Node.js 17.5.0 experimental native fetch API use --experimental-fetch flag.

`undici` support

In order to use experimental fetch implementation from nodejs/undici, You can import from ohmyfetch/undici.

import { $fetch } from 'ohmyfetch/undici'

On Node.js versions older than 16.5, node-fetch will be used as the fallback.

`keepAlive` support

By setting FETCH_KEEP_ALIVE environment variable to true, A http/https agent will be registred that keeps sockets around even when there are no outstanding requests, so they can be used for future requests without having to reestablish a TCP connection.

Note: This option can potentially introduce memory leaks. Please check node-fetch/node-fetch#1325.

✔️ Parsing Response

$fetch will smartly parse JSON and native values using destr, falling back to text if it fails to parse.

const { users } = await $fetch('/api/users')

For binary content types, $fetch will instead return a Blob object.

You can optionally provde a different parser than destr, or specify blob, arrayBuffer or text to force parsing the body with the respective FetchResponse method.

// Use JSON.parse
await $fetch('/movie?lang=en', { parseResponse: JSON.parse })

// Return text as is
await $fetch('/movie?lang=en', { parseResponse: txt => txt })

// Get the blob version of the response
await $fetch('/api/generate-image', { responseType: 'blob' })

✔️ JSON Body

$fetch automatically stringifies request body (if an object is passed) and adds JSON Content-Type and Accept headers (for put, patch and post requests).

const { users } = await $fetch('/api/users', { method: 'POST', body: { some: 'json' } })

✔️ Handling Errors

$fetch Automatically throw errors when response.ok is false with a friendly error message and compact stack (hiding internals).

Parsed error body is available with error.data. You may also use FetchError type.

await $fetch('http://google.com/404')
// FetchError: 404 Not Found (http://google.com/404)
//     at async main (/project/playground.ts:4:3)

In order to bypass errors as response you can use error.data:

await $fetch(...).catch((error) => error.data)

✔️ Auto Retry

$fetch Automatically retries the request if an error happens. Default is 1 (except for POST, PUT and PATCH methods that is 0)

await $fetch('http://google.com/404', {
  retry: 3
})

✔️ Type Friendly

Response can be type assisted:

const article = await $fetch<Article>(`/api/article/${id}`)
// Auto complete working with article.id

✔️ Adding `baseURL`

By using baseURL option, $fetch prepends it with respecting to trailing/leading slashes and query params for baseURL using ufo:

await $fetch('/config', { baseURL })

✔️ Adding params

By using params option, $fetch adds params to URL by preserving params in request itself using ufo:

await $fetch('/movie?lang=en', { params: { id: 123 } })

✔️ Interceptors

It is possible to provide async interceptors to hook into lifecycle events of fetch call.

You might want to use $fetch.create to set set shared interceptors.

`onRequest({ request, options })`

onRequest is called as soon as $fetch is being called, allowing to modify options or just do simple logging.

await $fetch('/api', {
  async onRequest({ request, options }) {
    // Log request
    console.log('[fetch request]', request, options)

    // Add `?t=1640125211170` to query params
    options.params = options.params
    options.params.t = new Date()
  }
})

`onRequestError({ request, options, error })`

onRequestError will be called when fetch request fails.

await $fetch('/api', {
  async onRequestError({ request, options, error }) {
    // Log error
    console.log('[fetch request error]', request, error)
  }
})

`onResponse({ request, options, response })`

onResponse will be called after fetch call and parsing body.

await $fetch('/api', {
  async onResponse({ request, response, options }) {
    // Log response
    console.log('[fetch response]', request, response.status, response.body)
  }
})

`onResponseError({ request, options, response })`

onResponseError is same as onResponse but will be called when fetch happens but response.ok is not true.

await $fetch('/api', {
  async onResponseError({ request, response, options }) {
    // Log error
    console.log('[fetch response error]', request, response.status, response.body)
  }
})

✔️ Create fetch with default options

This utility is useful if you need to use common options across serveral fetch calls.

Note: Defaults will be cloned at one level and inherrited. Be careful about nested options like headers.

const apiFetch = $fetch.create({ baseURL: '/api' })

apiFetch('/test') // Same as $fetch('/test', { baseURL: '/api' })

💡 Adding headers

By using headers option, $fetch adds extra headers in addition to the request default headers:

await $fetch('/movies', {
  headers: {
    Accept: 'application/json',
    'Cache-Control': 'no-cache'
  }
})

🍣 Access to Raw Response

If you need to access raw response (for headers, etc), can use $fetch.raw:

const response = await $fetch.raw('/sushi')

// response.data
// response.headers
// ...

📦 Bundler Notes

All targets are exported with Module and CommonJS format and named exports
No export is transpiled for sake of modern syntax
- You probably need to transpile ohmyfetch, destr and ufo packages with babel for ES5 support
You need to polyfill fetch global for supporting legacy browsers like using unfetch

❓ FAQ

Why export is called $fetch instead of fetch?

Using the same name of fetch can be confusing since API is different but still it is a fetch so using closest possible alternative. You can however, import { fetch } from ohmyfetch which is auto polyfilled for Node.js and using native otherwise.

Why not having default export?

Default exports are always risky to be mixed with CommonJS exports.

This also guarantees we can introduce more utils without breaking the package and also encourage using $fetch name.

Why not transpiled?

By keep transpiling libraries we push web backward with legacy code which is unneeded for most of the users.

If you need to support legacy users, you can optionally transpile the library in your build pipeline.

License

MIT. Made with 💖

GrabarzUndPartner/ohmyfetch