fetch

Voiceflow fetch wrapper and error handling for SDKs

Installation

yarn add --exact @voiceflow/fetch @voiceflow/exception

# if using for Node.JS
yarn add --exact undici

Usage

This is a universal library and can be used in the browser or in a Node.JS environment by passing a fetch implementation.

Browser Usage

import { FetchClient } from '@voiceflow/fetch';

const fetch = new FetchClient({
  /* config */
});

Node Usage

Make sure to install undici when using in a Node.JS environment.

yarn add --exact undici

import { FetchClient } from '@voiceflow/fetch/undici';

const fetch = new FetchClient({
  /* config */
});

Configuration

• baseURL (string): this will be added as a prefix to the URL of all requests

Features

• JSON requests
• JSON responses
• HTTP methods
• throws on non-2xx
• @voiceflow/exception integration
• raw request passthrough

JSON Requests

Use the json option to pass a payload that will be serialized with JSON.stringify. This will also automatically add the request header Content-Type: application/json.

const fetch = new FetchClient();

await fetch.put('http://example.com', {
  json: { foo: 'bar' },
});

JSON Responses

Use the json() method attached to the returned promise to resolve a parsed version of the response payload without needing an additional await. You can also specify a type for the parsed result, by default the type will be unknown.

const fetch = new FetchClient();

const result = await fetch.get('http://example.com').json<{ id: number; name: string }>();

HTTP Methods

Use the appropriate method to set the HTTP method being used in the request.

const fetch = new FetchClient();

fetch.delete('/foo'); // DELETE /foo
fetch.get('/foo'); // GET    /foo
fetch.head('/foo'); // HEAD   /foo
fetch.patch('/foo'); // PATCH  /foo
fetch.post('/foo'); // POST   /foo
fetch.put('/foo'); // PUT    /foo

Base URL

Specify a base URL which should be used to build every request.

const fetch = new FetchClient({ baseURL: 'http://example.com/' });

fetch.get('foo'); // GET http://example.com/foo

If you make a request using a URL instance then the baseURL option will be ignored.

const fetch = new FetchClient({ baseURL: 'http://example.com/' });
const url = new URL('http://foo.com/bar');

fetch.get(url); // GET http://foo.com/bar

Throws on non-2xx

If any non-2xx HTTP status is returned then a ClientException from @voiceflow/exception is thrown.

const fetch = new FetchClient();

try {
  await fetch.get('http://example.com'); // return 404
} catch (err) {
  err; // ClientException
}

@voiceflow/exception Integration

Internal error codes and other error details are automatically extracted from the response payload when a non-2xx status is returned.

import { ClientException } from '@voiceflow/exception';

const fetch = new FetchClient();

try {
  await fetch.get('http://example.com'); // return 404
} catch (err) {
  if (ClientException.instanceOf(err)) {
    err.errorCode; // ErrorCode | undefined
  }
}

Raw Request Passthrough

Use the raw() method to bypass all of the features above to access the underlying fetch interface directly.

Browser Native fetch Request

const fetch = new FetchClient();

const url = new URL('http://example.com');
const request = new Request(url);

const response = await fetch.raw(request); // Response

Node.JS Native undici.fetch Request

import { URL } from 'node:url';
import * as undici from 'undici';

const fetch = new FetchClient(undici.fetch);

const url = new URL('http://example.com');
const request = new undici.Request(url);

const response = await fetch.raw(request); // undici.Response