SuperAgent

SuperAgent is light-weight progressive ajax API crafted for flexibility, readability, and a low learning curve after being frustrated with many of the existing request APIs. It also works with Node.js!

 request
   .post('/api/pet')
   .send({ name: 'Manny', species: 'cat' })
   .set('X-API-Key', 'foobar')
   .set('Accept', 'application/json')
   .end(function(err, res){
     if (err || !res.ok) {
       alert('Oh no! error');
     } else {
       alert('yay got ' + JSON.stringify(res.body));
     }
   });

Test documentation

The following test documentation was generated with Mocha's "doc" reporter, and directly reflects the test suite. This provides an additional source of documentation.

Request basics

A request can be initiated by invoking the appropriate method on the request object, then calling .end() to send the request. For example a simple GET request:

 request
   .get('/search')
   .end(function(err, res){

   });

A method string may also be passed:

request('GET', '/search').end(callback);

ES6 promises are supported. Instead of .end() you can call .then():

request('GET', '/search').then(success, failure);

The Node client may also provide absolute URLs. In browsers absolute URLs won't work unless the server implements CORS.

 request
   .get('http://example.com/search')
   .end(function(err, res){

   });

The Node client supports making requests to Unix Domain Sockets:

 // pattern: https?+unix://SOCKET_PATH/REQUEST_PATH
 //          Use `%2F` as `/` in SOCKET_PATH
 request
   .get('http+unix://%2Fabsolute%2Fpath%2Fto%2Funix.sock/search')
   .end(function(err, res){

   });

DELETE, HEAD, PATCH, POST, and PUT requests can also be used, simply change the method name:

request
  .head('/favicon.ico')
  .end(function(err, res){

  });

DELETE can be also called as .del() for compatibility with old IE where delete is a reserved word.

The HTTP method defaults to GET, so if you wish, the following is valid:

 request('/search', function(err, res){

 });

Setting header fields

Setting header fields is simple, invoke .set() with a field name and value:

 request
   .get('/search')
   .set('API-Key', 'foobar')
   .set('Accept', 'application/json')
   .end(callback);

You may also pass an object to set several fields in a single call:

 request
   .get('/search')
   .set({ 'API-Key': 'foobar', Accept: 'application/json' })
   .end(callback);

GET requests

The .query() method accepts objects, which when used with the GET method will form a query-string. The following will produce the path /search?query=Manny&range=1..5&order=desc.

 request
   .get('/search')
   .query({ query: 'Manny' })
   .query({ range: '1..5' })
   .query({ order: 'desc' })
   .end(function(err, res){

   });

Or as a single object:

request
  .get('/search')
  .query({ query: 'Manny', range: '1..5', order: 'desc' })
  .end(function(err, res){

  });

The .query() method accepts strings as well:

  request
    .get('/querystring')
    .query('search=Manny&range=1..5')
    .end(function(err, res){

    });

Or joined:

  request
    .get('/querystring')
    .query('search=Manny')
    .query('range=1..5')
    .end(function(err, res){

    });

HEAD requests

You can also use the .query() method for HEAD requests. The following will produce the path /users?email=joe@smith.com.

  request
    .head('/users')
    .query({ email: 'joe@smith.com' })
    .end(function(err, res){

    });

POST / PUT requests

A typical JSON POST request might look a little like the following, where we set the Content-Type header field appropriately, and "write" some data, in this case just a JSON string.

  request.post('/user')
    .set('Content-Type', 'application/json')
    .send('{"name":"tj","pet":"tobi"}')
    .end(callback)

Since JSON is undoubtably the most common, it's the default! The following example is equivalent to the previous.

  request.post('/user')
    .send({ name: 'tj', pet: 'tobi' })
    .end(callback)

Or using multiple .send() calls:

  request.post('/user')
    .send({ name: 'tj' })
    .send({ pet: 'tobi' })
    .end(callback)

By default sending strings will set the Content-Type to application/x-www-form-urlencoded, multiple calls will be concatenated with &, here resulting in name=tj&pet=tobi:

  request.post('/user')
    .send('name=tj')
    .send('pet=tobi')
    .end(callback);

SuperAgent formats are extensible, however by default "json" and "form" are supported. To send the data as application/x-www-form-urlencoded simply invoke .type() with "form", where the default is "json". This request will POST the body "name=tj&pet=tobi".

  request.post('/user')
    .type('form')
    .send({ name: 'tj' })
    .send({ pet: 'tobi' })
    .end(callback)

Setting the Content-Type

The obvious solution is to use the .set() method:

 request.post('/user')
   .set('Content-Type', 'application/json')

As a short-hand the .type() method is also available, accepting the canonicalized MIME type name complete with type/subtype, or simply the extension name such as "xml", "json", "png", etc:

 request.post('/user')
   .type('application/json')

 request.post('/user')
   .type('json')

 request.post('/user')
   .type('png')

Serializing request body

SuperAgent will automatically serialize JSON and forms. If you want to send the payload in a custom format, you can replace the built-in serialization with .serialize() method.

Setting Accept

In a similar fashion to the .type() method it is also possible to set the Accept header via the short hand method .accept(). Which references request.types as well allowing you to specify either the full canonicalized MIME type name as type/subtype, or the extension suffix form as "xml", "json", "png", etc. for convenience:

 request.get('/user')
   .accept('application/json')

 request.get('/user')
   .accept('json')

 request.post('/user')
   .accept('png')

Facebook and Accept JSON

If you are calling Facebook's API, be sure to send an Accept: application/json header in your request. If you don't do this, Facebook will respond with Content-Type: text/javascript; charset=UTF-8, which SuperAgent will not parse and thus res.body will be undefined. You can do this with either req.accept('json') or req.header('Accept', 'application/json'). See issue 1078 for details.

Query strings

res.query(obj) is a method which may be used to build up a query-string. For example populating ?format=json&dest=/login on a POST:

request
  .post('/')
  .query({ format: 'json' })
  .query({ dest: '/login' })
  .send({ post: 'data', here: 'wahoo' })
  .end(callback);

By default the query string is not assembled in any particular order. An asciibetically-sorted query string can be enabled with req.sortQuery(). You may also provide a custom sorting comparison function with req.sortQuery(myComparisonFn). The comparison function should take 2 arguments and return a negative/zero/positive integer.

 // default order
 request.get('/user')
   .query('name=Nick')
   .query('search=Manny')
   .sortQuery()
   .end(callback)

 // customized sort function
 request.get('/user')
   .query('name=Nick')
   .query('search=Manny')
   .sortQuery(function(a, b){
     return a.length - b.length;
   })
   .end(callback)

Parsing response bodies

SuperAgent will parse known response-body data for you, currently supporting application/x-www-form-urlencoded, application/json, and multipart/form-data.

You can set a custom parser (that takes precedence over built-in parsers) with the .buffer(true).parse(fn) method. If response buffering is not enabled (.buffer(false)) then the response event will be emitted without waiting for the body parser to finish, so response.body won't be available.

JSON / Urlencoded

The property res.body is the parsed object, for example if a request responded with the JSON string '{"user":{"name":"tobi"}}', res.body.user.name would be "tobi". Likewise the x-www-form-urlencoded value of "user[name]=tobi" would yield the same result. Only one level of nesting is supported. If you need more complex data, send JSON instead.

Arrays are sent by repeating the key. .send({color: ['red','blue']}) sends color=red&color=blue. If you want the array keys to contain [] in their name, you must add it yourself, as SuperAgent doesn't add it automatically.

Multipart

The Node client supports multipart/form-data via the Formidable module. When parsing multipart responses, the object res.files is also available to you. Suppose for example a request responds with the following multipart body:

--whoop
Content-Disposition: attachment; name="image"; filename="tobi.png"
Content-Type: image/png

... data here ...
--whoop
Content-Disposition: form-data; name="name"
Content-Type: text/plain

Tobi
--whoop--

You would have the values res.body.name provided as "Tobi", and res.files.image as a File object containing the path on disk, filename, and other properties.

Binary

In browsers, you may use .responseType('blob') to request handling of binary response bodies. This API is unnecessary when running in node.js. The supported argument values for this method are

req.get('/binary.data')
  .responseType('blob')
  .end(function (error, res) {
    // res.body will be a browser native Blob type here
  });

For more information, see the Mozilla Developer Network xhr.responseType docs.

Response properties

Many helpful flags and properties are set on the Response object, ranging from the response text, parsed response body, header fields, status flags and more.

Response text

The res.text property contains the unparsed response body string. This property is always present for the client API, and only when the mime type matches "text/", "/json", or "x-www-form-urlencoded" by default for node. The reasoning is to conserve memory, as buffering text of large bodies such as multipart files or images is extremely inefficient.

To force buffering see the "Buffering responses" section.

Response body

Much like SuperAgent can auto-serialize request data, it can also automatically parse it. When a parser is defined for the Content-Type, it is parsed, which by default includes "application/json" and "application/x-www-form-urlencoded". The parsed object is then available via res.body.

Response header fields

The res.header contains an object of parsed header fields, lowercasing field names much like node does. For example res.header['content-length'].

Response Content-Type

The Content-Type response header is special-cased, providing res.type, which is void of the charset (if any). For example the Content-Type of "text/html; charset=utf8" will provide "text/html" as res.type, and the res.charset property would then contain "utf8".

Response status

The response status flags help determine if the request was a success, among other useful information, making SuperAgent ideal for interacting with RESTful web services. These flags are currently defined as:

 var type = status / 100 | 0;

 // status / class
 res.status = status;
 res.statusType = type;

 // basics
 res.info = 1 == type;
 res.ok = 2 == type;
 res.clientError = 4 == type;
 res.serverError = 5 == type;
 res.error = 4 == type || 5 == type;

 // sugar
 res.accepted = 202 == status;
 res.noContent = 204 == status || 1223 == status;
 res.badRequest = 400 == status;
 res.unauthorized = 401 == status;
 res.notAcceptable = 406 == status;
 res.notFound = 404 == status;
 res.forbidden = 403 == status;

Aborting requests

To abort requests simply invoke the req.abort() method.

Request timeouts

A timeout can be applied by invoking req.timeout(ms), after which an error will be triggered. To differentiate between other errors the err.timeout property is set to the ms value. NOTE that this is a timeout applied to the request and all subsequent redirects, not per request.

Authentication

In both Node and browsers auth available via the .auth() method:

request
  .get('http://local')
  .auth('tobi', 'learnboost')
  .end(callback);

In the Node client Basic auth can be in the URL as "user:pass":

request.get('http://tobi:learnboost@local').end(callback);

By default only Basic auth is used. In browser you can add {type:'auto'} to enable all methods built-in in the browser (Digest, NTLM, etc.):

request.auth('digest', 'secret', {type:'auto'})

Following redirects

By default up to 5 redirects will be followed, however you may specify this with the res.redirects(n) method:

request
  .get('/some.png')
  .redirects(2)
  .end(callback);

Preserving cookies

In Node SuperAgent does not save cookies by default, but you can use the .agent() method to create a copy of SuperAgent that saves cookies. Each copy has a separate cookie jar.

const agent = request.agent();
agent
  .post('/login')
  .then(() => {
    return agent.get('/cookied-page');
  });

In browsers cookies are managed automatically by the browser, and there is no .agent() method.

Piping data

The Node client allows you to pipe data to and from the request. For example piping a file's contents as the request:

const request = require('superagent');
const fs = require('fs');

const stream = fs.createReadStream('path/to/my.json');
const req = request.post('/somewhere');
req.type('json');
stream.pipe(req);

Or piping the response to a file:

const stream = fs.createWriteStream('path/to/my.json');
const req = request.get('/some.json');
req.pipe(stream);

Multipart requests

SuperAgent is also great for building multipart requests for which it provides methods .attach() and .field().

Attaching files

As mentioned a higher-level API is also provided, in the form of .attach(name, [path], [filename]) and .field(name, value)/.field(object). Attaching several files is simple, you can also provide a custom filename for the attachment, otherwise the basename of the attached file is used.

request
  .post('/upload')
  .attach('avatar', 'path/to/tobi.png', 'user.png')
  .attach('image', 'path/to/loki.png')
  .attach('file', 'path/to/jane.png')
  .end(callback);

Field values

Much like form fields in HTML, you can set field values with the .field(name, value) method. Suppose you want to upload a few images with your name and email, your request might look something like this:

 request
   .post('/upload')
   .field('user[name]', 'Tobi')
   .field('user[email]', 'tobi@learnboost.com')
   .field('friends[]', ['loki', 'jane'])
   .attach('image', 'path/to/tobi.png')
   .end(callback);

Compression

The node client supports compressed responses, best of all, you don't have to do anything! It just works.

Buffering responses

To force buffering of response bodies as res.text you may invoke req.buffer(). To undo the default of buffering for text responses such as "text/plain", "text/html" etc you may invoke req.buffer(false).

When buffered the res.buffered flag is provided, you may use this to handle both buffered and unbuffered responses in the same callback.

CORS

For security reasons, browsers will block cross-origin requests unless the server opts-in using CORS headers. Browsers will also make extra OPTIONS requests to check what HTTP headers and methods are allowed by the server. Read more about CORS.

The .withCredentials() method enables the ability to send cookies from the origin, however only when Access-Control-Allow-Origin is not a wildcard ("*"), and Access-Control-Allow-Credentials is "true".

request
  .get('http://api.example.com:4001/')
  .withCredentials()
  .then(function(res){
    assert.equal(200, res.status);
    assert.equal('tobi', res.text);
  })

Error handling

Your callback function will always be passed two arguments: error and response. If no error occurred, the first argument will be null:

request
 .post('/upload')
 .attach('image', 'path/to/tobi.png')
 .end(function(err, res){

 });

 An "error" event is also emitted, with you can listen for:

request
  .post('/upload')
  .attach('image', 'path/to/tobi.png')
  .on('error', handle)
  .end(function(err, res){

  });

Note that a 4xx or 5xx response with super agent are considered an error by default. For example if you get a 500 or 403 response, this status information will be available via err.status. Errors from such responses also contain an err.response field with all of the properties mentioned in "Response properties". The library behaves in this way to handle the common case of wanting success responses and treating HTTP error status codes as errors while still allowing for custom logic around specific error conditions.

Network failures, timeouts, and other errors that produce no response will contain no err.status or err.response fields.

If you wish to handle 404 or other HTTP error responses, you can query the err.status property. When an HTTP error occurs (4xx or 5xx response) the res.error property is an Error object, this allows you to perform checks such as:

if (err && err.status === 404) {
  alert('oh no ' + res.body.message);
}
else if (err) {
  // all other error types we handle generically
}

Promise and Generator support

SuperAgent's request is a "thenable" object that's compatible with JavaScript promises and async/await syntax. Do not call .end() if you're using promises.

Libraries like co or a web framework like koa can yield on any SuperAgent method:

const req = request
  .get('http://local')
  .auth('tobi', 'learnboost');
const res = yield req;

Note that SuperAgent expects the global Promise object to be present. You'll need a polyfill to use promises in Internet Explorer or Node.js 0.10.

Browser and node versions

SuperAgent has two implementations: one for web browsers (using XHR) and one for Node.JS (using core http module). By default Browserify and WebPack will pick the browser version.

If want to use WebPack to compile code for Node.JS, you must specify node target in its configuration.

Using browser version in electron

Electron developers report if you would prefer to use the browser version of SuperAgent instead of the Node version, you can require('superagent/superagent'). Your requests will now show up in the Chrome developer tools Network tab. Note this environment is not covered by automated test suite and not officially supported.

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