@mojojs/user-agent


A powerful user-agent for Node.js and browsers. Written in TypeScript. VERY EXPERIMENTAL!

``js
import UserAgent from '@mojojs/user-agent';

const ua = new UserAgent();
const res = await ua.get('https://mojolicious.org');
const dom = await res.html();
const title = dom.at('title').text();
`

The API is heavily inspired by the Fetch Standard and should feel familar if you've
used fetch before.

$3

The user-agent can be initialized with a few options, but none of them are required.

`js
const ua = new UserAgent({

// Base URL to be used to resolve all relative request URLs with
baseURL: 'http://127.0.0.1:3000',

// Disable TLS certificate validation (only Node.js)
insecure: true,

// Keep-alive timeout, disabled with null, defaults to 1000 (only Node.js)
keepAlive: 3000,

// Maximum number of redirects to follow, defaults to 20 (only Node.js)
maxRedirects: 5,

// Name of user-agent to send with User-Agent header (only Node.js)
name: 'mojoUA/1.0'
});
`

$3

Every request is represented by a config object that contains various properties to describe every part of the HTTP
request.

`js
const res = await ua.request({

// HTTP method for request
method: 'GET',

// URL of request target as a string or URL object, may be be relative to ua.baseURL
url: new URL('https://mojolicious.org'),

// Headers to include in request
headers: {Accept: '/', Authorization: 'token 123456789abcdef'},

// Object with key/value pairs to be sent with the query string
query: {fieldA: 'first value', fieldB: 'second value'},

// Request body as a string
body: 'Some content to send with request',

// Data structure to be send in JSON format
json: {hello: ['world']},

// Object with key/value pairs to be sent in application/x-www-form-urlencoded format
form: {fieldA: 'first value', fieldB: 'second value'},

// Object with key/value pairs or FormData object to be sent in multipart/form-data format
formData: {fieldA: 'first value', fieldB: 'second value', fieldC: {content: 'third value', filename: 'foo.txt'}},

// Basic authentication
auth: 'user:password',

// An AbortSignal to abort the request
signal: controller.signal
});
`

The request method returns a Promise that resolves with a response object, right after the response
status line and headers have been received. But before any data from the response body has been read, which can be
handled in a separate step later on.

$3

Since every request includes at least method and url values, there are HTTP method specific shortcuts you can use
instead of request.

`js
const res = await ua.delete('https://mojolicious.org');
const res = await ua.get('https://mojolicious.org');
const res = await ua.head('https://mojolicious.org');
const res = await ua.options('https://mojolicious.org');
const res = await ua.patch('https://mojolicious.org');
const res = await ua.post('https://mojolicious.org');
const res = await ua.put('https://mojolicious.org');
`

All remaining config values can be passed with a second argument to any one of the shortcut methods.

`js
const res = await ua.post('/search', {form: {q: 'mojo'}});
`

$3

Status line information and response headers are available right away with the response object.

`js
// Status code and message
const statusCode = res.statusCode;
const statusMessage = res.statusMessage;

// Headers
const contentType = res.get('Content-Type');

// 2xx
const isSuccess = res.isSuccess;

// 3xx
const isRedirect = res.isRedirect;

// 4xx
const isClientError = res.isClientError;

// 5xx
const isServerError = res.isServerError;

// 4xx or 5xx
const isError = res.isError;
`

$3

The reponse body can be received in various formats. Most of them will result once again in a new Promise, resolving
to different results however.

`js
// ReadableStream
const stream = res.body;

// String
const text = await res.text();

// Uint8Array
const data = await res.data();

// Parsed JSON
const data = await res.json();

// Parsed HTML via @mojojs/dom
const dom = await res.html();
const title = dom.at('title').text();

// Parsed XML via @mojojs/dom
const dom = await res.xml();

// stream.Readable (only Node.js)
const stream = res.createReadStream();

// Pipe content to stream.Writable object (only Node.js)
await res.pipe(process.stdout);
`

For HTML and XML parsing @mojojs/dom will be used. Making it very easy to
extract information from documents with just a CSS selector and almost no code at all.

$3

By default, for Node.js, a tough-cookie based cookie jar will be used for
state keeping, and you can reconfigure it however you like.

`js
ua.httpTransport.cookieJar.allowSpecialUseDomain = true;
`

Of course you can also just disable cookies completely.

`js
ua.httpTransport.cookieJar = null;
`

In browsers the native browser cookie jar will be used instead.

$3

Hooks can be used to extend the user-agent and run code for every HTTP request.

`js
// Add a header to every HTTP request
ua.addHook('request', async (ua, config) => {
config.headers['X-Bender'] = 'Bite my shiny metal ass!';
});

// Add a query parameter to every HTTP request
ua.addHook('request', async (ua, config) => {
config.url.searchParams.append('hello', 'mojo');
});
`

$3

You can use an AbortController to make sure a request does not take longer than a certain amount of time. Once
aborted the promise returned by ua.get() will reject.

`js
const controller = new AbortController();
const signal = controller.signal;
setTimeout(() => controller.abort(), 3000);
const res = await ua.get('https://mojojs.org', {signal});
`

$3

Responses with gzip or deflate content encoding will be decompressed transparently.

$3

With Node.js you can set the MOJO_CLIENT_DEBUG environment variable to get some advanced diagnostics information
printed to STDERR.

`
$ MOJO_CLIENT_DEBUG=1 node myapp.js
-- Client >>> Server
GET /hello.html
accept: /
accept-language: *
sec-fetch-mode: cors
accept-encoding: gzip, deflate

-- Client <<< Server
200 OK
Content-Type: text/plain; charset=utf-8
Content-Length: 12
Date: Mon, 02 May 2022 23:32:34 GMT
Connection: close

Hello World!
`

Installation

All you need is Node.js 18 (or newer).

`
$ npm install @mojojs/user-agent
``

Support

If you have any questions the documentation might not yet answer, don't hesitate to ask in the
Forum, on Matrix, or
IRC.