supreme-ajax

supreme-ajax

Immutable-style AJAX library for the browser

Principles

• Immutable API
• Promise-based
• Throws meaningful errors
• Understands Content-Type
  • Decodes JSON responses by default
• Works on modern browsers
  • No external dependencies
  • See polyfills for a list of polyfills you might need for older browsers
• Fully tested

Installation

Install via npm or yarn:

npm install supreme-ajax
# or
yarn add supreme-ajax

Import in a project:

import request from 'supreme-ajax';
// or
const request = require('supreme-ajax');

Usage

See these basic examples or the full API below.

// Make a GET request
request
  .get('https://example.com')
  .query({ foo: 'bar' })
  .send()
  .then(response => {
    console.log(response.body);
  })
  .catch(error => {
    console.error(error.response.status);
  })

// Make a POST request
request
  .post('https://example.com/accounts')
  .body('raw data')
  .send()

// Make a POST request (json)
request
  .post('https://example.com/accounts')
  .json({ foo: 'bar' })
  .send()

// Make a POST request (urlencoded)
request
  .post('https://example.com/accounts')
  .urlencoded({ foo: 'bar' })
  .send()

// Set a base URL
request
  .baseUrl('https://example.com')
  .get('/accounts')
  .send()

// Set headers
request
  .get('https://example.com')
  .headers({
    'X-Random': 1
  })
  .header('x-another', 'test')
  .unsetHeader('x-another')
  .send()

// Set a timeout
request
  .get('https://example.com')
  .timeout(2000)
  .send()

// JSON responses decoded automatically based on Content-Type header (can be turned off)
request
  .get('https://example.com/accounts.json')
  .send()
  .then(response => {
    console.log(response.data);
  })

// Bring your own Promise
request
  .polyfills({ Promise: require('bluebird') })
  .get('https://example.com')
  .send()

Extending

Each method of ImmutableAjaxRequest returns a new instance of ImmutableAjaxRequest. This is demonstrated in the example below.

The example uses toObject which returns a copy of all configuration of that specific instance at that moment in time.

const req1 = request
  .get('https://example.com')
  .query({ foo: 'bar' });

// Extend from previous request
const req2 = req1.query({ something: 'different' });

console.log(req2 === req1); // => false
console.log(req1.toObject().query); // => 'foo=bar'
console.log(req2.toObject().query); // => 'something=different'

Practical example of how to create a base request with some defaults and later utilize it for requests:

const api = request
  .baseUrl('https://example.com/api/v1')
  .headers({
    'X-API-KEY': 'secret123'
  });

// The following requests will use the base URL and headers set above
api.get('/accounts').send();
api.post('/accounts').body(data).send();

Inspect request config

Use the API methods toObject, config or debug to inspect the configuration of an ImmutableAjaxRequest instance.

const req = request.get('https://example.com');
console.log(req.toObject().url);

API

The following methods are available.

get

.get(url)

Where url is a string. Shorthand for request.method('get').url(url).

post

.post(url)

Where url is a string. Shorthand for request.method('post').url(url).

method

Sets the HTTP method.

.method(method)

Where method is a string, e.g. 'get' or 'GET'.

url

Sets the full URL of the request. If a query-string is present, it will override any previously set query parameters.

.url(url)

Where url is a string, e.g. 'https://example.com/accounts'.

baseUrl

Sets the base URL to which all subsequent request URLs will be appended.

.baseUrl(url)

Where url is a string, e.g. 'https://example.com'.

Refer to URL documentation to see how baseUrl and url behave. A few examples:

request.baseUrl('https://example.com').url('accounts')    // => https://example.com/accounts
request.baseUrl('https://example.com/').url('accounts')   // => https://example.com/accounts
request.baseUrl('https://example.com').url('/accounts')   // => https://example.com/accounts
request.baseUrl('https://example.com/').url('/accounts')  // => https://example.com/accounts
request.baseUrl('https://example.com/nested').url('accounts')      // => https://example.com/accounts
request.baseUrl('https://example.com/nested').url('/accounts')     // => https://example.com/accounts
request.baseUrl('https://example.com/nested/').url('accounts')     // => https://example.com/nested/accounts
request.baseUrl('https://example.com/nested/foo').url('accounts')  // => https://example.com/nested/accounts

query

Sets query parameters from an object. Overwrites existing query.

.query(object)

Where object is key-value object of query parameters to set (will be encoded using URLSearchParams#toString), or a valid query string.

headers

Sets request headers from an object. Overwrites existing headers.

.headers(object)

Where object is key-value object of headers to set.

Example:

const req = request.headers({ 'x-example': 'foo' });
console.log(req.toObject().headers) // => { 'x-example': 'foo' }
// Overwrites all previous headers:
const req2 = req.headers({ 'x-token': 'secret123' });
console.log(req2.toObject().headers) // => { 'x-token': 'secret123' }

amendHeaders

Sets request headers from an object. Only overwrites headers present in the given object.

.amendHeaders(object)

Where object is key-value object of headers to set.

Example:

const req = request.headers({ 'x-example': 'foo' }).amendHeaders({ 'x-token': 'secret123' });
console.log(req.toObject().headers) // => { 'x-example': 'foo', 'x-token': 'secret123' }

header

Adds or updates a header value.

.header(key, value)

Where key is a string and value is a string.

Example:

const req = request.header('x-example', 'foo').header('x-token', 'secret123');
console.log(req.toObject().headers) // => { 'x-example': 'foo', 'x-token': 'secret123' }

unsetHeader

Removes a header from the request.

.unsetHeader(name)

Where name is a string.

Example:

const req = request.headers({ 'x-example': 'foo', 'x-token': 'secret123' }).unsetHeader('x-example');
console.log(req.toObject().headers) // => { 'x-token': 'secret123' }

body

Set the body of the request.

.body(data)

Where data is a string.

See also json and urlencoded.

json

Sets a JSON-encoded body and sets the Content-Type header to 'application/json'.

.json(value)

Where value is mixed.

Shorthand for request.header('Content-Type', 'application/json').body(JSON.stringify(value)).

urlencoded

Sets a JSON-encoded body and sets the Content-Type header to 'application/urlencoded'.

.urlencoded(value)

Where value is mixed.

Shorthand for request.header('content-type', 'application/x-www-form-urlencoded').body(_valueUrlEncoded_).

timeout

Sets a timeout after which the request will be aborted and the Promise rejected.

.timeout(milliseconds)

Where milliseconds is an integer.

See also unsetTimeout.

unsetTimeout

Removes the timeout-value previously set with timeout.

.unsetTimeout()

send

Dispatches the request and returns a Promise.

.send([body])

Where the optional argument body is a string. If it is set, it will be set as the request body. Also see sendJson and sendUrlencoded.

The Promise resolves with a response object.

request
  .get('https://example.com')
  .then(response => {
    console.log(response.headers); // object
    console.log(response.body); // string
    console.log(response.status); // integer
  })
  .catch(error => {
    console.log(error.message);
    console.log(error.response); // Similar structure as successful response
  })

A new Promise is always returned, and the ImmutableAjaxRequest is not mutated, so you can send the same request multiple times.

const req = request.get('https://example.com');
req.send().then(response => {
  console.log('first response', response);
});
req.send().then(() => {
  console.log('second response', response);
});

See polyfills for switching away from global Promise (e.g. bluebird).

sendUrlencoded

Short-hand for .urlencoded(data).send().

.sendUrlencoded(data)

sendJson

Short-hand for .json(data).send().

.sendJson(data)

setResponseTransformers

Sets a list of response transformers which are called when a response is received. By default the list contains one transformer which decodes JSON bodies based on the response Content-Type header.

Using this method you can remove the default transformer:

.setResponseTransformers([])

If you need to add it back, just set it again:

request.setResponseTransformers([ request.jsonResponseTransformer ]);

Transformer functions are executed sequentially in the order they are in the list, and they receive response as the only parameter. Whatever value they return is passed onto the next transformer and eventually back to the Promise-chain.

request.setResponseTransformers([
  response => {
    response.foobar = 'some extra information from elsewhere, for example';
    return response;
  }
]);

setAllowedStatusCode

By default any 2XX status code resolves the Promise and other status codes will reject it. This can be customized using setAllowedStatusCode.

.setAllowedStatusCode(allowed)

Where allowed is an integer, a RegExp or a function.

polyfills

Override global dependencies which are used internally. Most useful for adding polyfills or a custom Promise-implementation.

.polyfills(polyfills)

Where polyfills is an object. See example for the possible dependencies you can override:

request.polyfills({
  Promise: window.Promise,
  URLSearchParams: window.URLSearchParams
})

Links to polyfills for older browsers if you need to support them (these automatically patch window.Promise and window.URLSearchParams; no need to use request.polyfills):

• es6-promise
• url-search-params

toObject

Returns the request configuration as an object.

.toObject()
.config() // alias
.debug() // alias

Example:

const req = request.baseUrl('http://example.com').get('/info').header('X-Random', 'foo')
const config = req.toObject(); // or req.config() or req.debug()
// =>
// {
//   method: 'GET',
//   url: 'http://example.com/info',
//   body: '',
//   headers: {
//     'x-random': 'foo'
//   },
//   allowedStatusCode: /^2[0-9]{2}$/,
//   timeout: null,
//   responseTransformers: [
//     req.jsonResponseTransformer
//   ],
// }

Development

Tests

For testing during development, the following command starts a web server which servers a web-based mocha runner:

$ yarn build # Tests are run against the minified library
$ yarn mocha
Test server is running!
Open http://localhost:8080/ in your browser

Run full test suite, which runs the same mocha tests in all browsers via karma, among other things:

yarn test