Axios: Promise Based HTTP Client

Axios is a promise-based JavaScript library, which gives you the ability to take advantage of JavaScript’s async and await for more readable asynchronous code. It can be used in both browser and Node.js to make HTTP requests.

#axios #http-client #api #javascript #fetch

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Axios: Promise Based HTTP Client

Axios is a promise-based JavaScript library, which gives you the ability to take advantage of JavaScript’s async and await for more readable asynchronous code. It can be used in both browser and Node.js to make HTTP requests.

#axios #http-client #api #javascript #fetch

Axios HTTP Client Example | Axios POST, GET Requests

Axios HTTP Client is the Promise based HTTP client for the browser and node.js. Axios HTTP Client will teach you how to use Axios POST request to the server or Axios GET request to fetch the data. It supports all modern browsers, including support for IE8 and higher.

It is promise-based, and this lets us write async/await code to perform XHR requests very quickly. Using Axios, It is effortless to send an asynchronous HTTP request to the server or REST endpoints and perform any CRUD operations.

Javascript Axios library can be used in your everyday JavaScript application or can be used together with more advanced frameworks like  Vue.js,  Angular, or  Node.js.

Axios has lots of advantages over the native  Fetch API:

• It supports older browsers (Fetch needs a polyfill)
• It has a way to abort a request.
• It has a way to set a response timeout.
• It has built-in CSRF protection.
• It supports upload progress.
• It performs automatic JSON data transformation.
• It works with Node.js very well.

In this tutorial, you’ll learn how to install and add Axios to your project and perform an asynchronous HTTP request. We’ll cover a real-world scenario throughout this example.

#javascript axios #axios http client #node.js #vue.js #angular

HTTP requests using Axios

The most common way for frontend programs to communicate with servers is through the HTTP protocol. You are probably familiar with the Fetch API and the XMLHttpRequest interface, which allow you fetch resources and make HTTP requests.

If you are using a JavaScript library, chances are it comes with a client HTTP API. jQuery’s $.ajax() function, for example, has been particularly popular with frontend developers. But as developers move away from such libraries in favor of native APIs, dedicated HTTP clients have emerged to fill the gap.

In this post we will take a good look at Axios, a client HTTP API based on the XMLHttpRequest interface provided by browsers, and examine the key features that has contributed to its rise in popularity among frontend developers.

Why Axios?

As with Fetch, Axios is promise-based. However, it provides a more powerful and flexible feature set. Advantages over the native Fetch API include:

• Request and response interception
• Streamlined error handling
• Protection against XSRF
• Support for upload progress
• Response timeout
• The ability to cancel requests
• Support for older browsers
• Automatic JSON data transformation

Installation

You can install Axios using:

• npm:

$ npm install axios

• The Bower package manager:

$ bower install axios

• Or a content delivery network:

<script src="https://unpkg.com/axios/dist/axios.min.js"></script>

Making requests

Making an HTTP request is as easy as passing a config object to the Axios function. In its simplest form, the object must have a url property; if no method is provided, GET will be used as the default value. Let’s look at a simple example:

// send a POST request
axios({
  method: 'post',
  url: '/login',
  data: {
    firstName: 'Finn',
    lastName: 'Williams'
  }
});

This should look familiar to those who have worked with jQuery’s $.ajax function. This code is simply instructing Axios to send a POST request to /login with an object of key/value pairs as its data. Axios will automatically convert the data to JSON and send it as the request body.

Shorthand methods

Axios also provides a set of shorthand methods for performing different types of requests. The methods are as follows:

• axios.request(config)
• axios.get(url[, config])
• axios.delete(url[, config])
• axios.head(url[, config])
• axios.options(url[, config])
• axios.post(url[, data[, config]])
• axios.put(url[, data[, config]])
• axios.patch(url[, data[, config]])

For instance, the following code shows how the previous example could be written using the axios.post() method:

axios.post('/login', {
  firstName: 'Finn',
  lastName: 'Williams'
});

Handling the response

Once an HTTP request is made, Axios returns a promise that is either fulfilled or rejected, depending on the response from the backend service. To handle the result, you can use the then() method like this:

axios.post('/login', {
  firstName: 'Finn',
  lastName: 'Williams'
})
.then((response) => {
  console.log(response);
}, (error) => {
  console.log(error);
});

If the promise is fulfilled, the first argument of then() will be called; if the promise is rejected, the second argument will be called. According to the documentation, the fulfillment value is an object containing the following information:

{
  // `data` is the response that was provided by the server
  data: {},
 
  // `status` is the HTTP status code from the server response
  status: 200,
 
  // `statusText` is the HTTP status message from the server response
  statusText: 'OK',
 
  // `headers` the headers that the server responded with
  // All header names are lower cased
  headers: {},
 
  // `config` is the config that was provided to `axios` for the request
  config: {},
 
  // `request` is the request that generated this response
  // It is the last ClientRequest instance in node.js (in redirects)
  // and an XMLHttpRequest instance the browser
  request: {}
}

As an example, here’s how the response looks when requesting data from the GitHub API:

axios.get('https://api.github.com/users/mapbox')
  .then((response) => {
    console.log(response.data);
    console.log(response.status);
    console.log(response.statusText);
    console.log(response.headers);
    console.log(response.config);
  });

// logs:
// => {login: "mapbox", id: 600935, node_id: "MDEyOk9yZ2FuaXphdGlvbjYwMDkzNQ==", avatar_url: "https://avatars1.githubusercontent.com/u/600935?v=4", gravatar_id: "", …}
// => 200
// => OK
// => {x-ratelimit-limit: "60", x-github-media-type: "github.v3", x-ratelimit-remaining: "60", last-modified: "Wed, 01 Aug 2018 02:50:03 GMT", etag: "W/"3062389570cc468e0b474db27046e8c9"", …}
// => {adapter: ƒ, transformRequest: {…}, transformResponse: {…}, timeout: 0, xsrfCookieName: "XSRF-TOKEN", …}

Making simultaneous requests

One of Axios’ more interesting features is its ability to make multiple requests in parallel by passing an array of arguments to the axios.all() method. This method returns a single promise object that resolves only when all arguments passed as an array have resolved. Here’s a simple example:

// execute simultaneous requests 
axios.all([
  axios.get('https://api.github.com/users/mapbox'),
  axios.get('https://api.github.com/users/phantomjs')
])
.then(responseArr => {
  //this will be executed only when all requests are complete
  console.log('Date created: ', responseArr[0].data.created_at);
  console.log('Date created: ', responseArr[1].data.created_at);
});

// logs:
// => Date created:  2011-02-04T19:02:13Z
// => Date created:  2017-04-03T17:25:46Z

This code makes two requests to the GitHub API and then logs the value of the created_at property of each response to the console. Keep in mind that if any of the arguments rejects then the promise will immediately reject with the reason of the first promise that rejects.

For convenience, Axios also provides a method called axios.spread() to assign the properties of the response array to separate variables. Here’s how you could use this method:

axios.all([
  axios.get('https://api.github.com/users/mapbox'),
  axios.get('https://api.github.com/users/phantomjs')
])
.then(axios.spread((user1, user2) => {
  console.log('Date created: ', user1.data.created_at);
  console.log('Date created: ', user2.data.created_at);
}));

// logs:
// => Date created:  2011-02-04T19:02:13Z
// => Date created:  2017-04-03T17:25:46Z

The output of this code is the same as the previous example. The only difference is that the axios.spread() method is used to unpack values from the response array.

Sending custom headers

Sending custom headers with Axios is very straightforward. Simply pass an object containing the headers as the last argument. For example:

const options = {
  headers: {'X-Custom-Header': 'value'}
};

axios.post('/save', { a: 10 }, options);

Transforming requests and responses

By default, Axios automatically converts requests and responses to JSON. But it also allows you to override the default behavior and define a different transformation mechanism. This ability is particularly useful when working with an API that accepts only a specific data format such as XML or CSV.

To change the request data before sending it to the server, set the transformRequest property in the config object. Note that this method only works for PUT, POST, and PATCH request methods. Here’s how you can do that:

const options = {
  method: 'post',
  url: '/login',
  data: {
    firstName: 'Finn',
    lastName: 'Williams'
  },
  transformRequest: [(data, headers) => {
    // transform the data

    return data;
  }]
};

// send the request
axios(options);

To modify the data before passing it to then() or catch(), you can set the transformResponse property:

const options = {
  method: 'post',
  url: '/login',
  data: {
    firstName: 'Finn',
    lastName: 'Williams'
  },
  transformResponse: [(data) => {
    // transform the response

    return data;
  }]
};

// send the request
axios(options);

Intercepting requests and responses

HTTP Interception is a popular feature of Axios. With this feature, you can examine and change HTTP requests from your program to the server and vice versa, which is very useful for a variety of implicit tasks, such as logging and authentication.

At first glance, interceptors look very much like transforms, but they differ in one key way: unlike transforms, which only receive the data and headers as arguments, interceptors receive the entire response object or request config.

You can declare a request interceptor in Axios like this:

// declare a request interceptor
axios.interceptors.request.use(config => {
  // perform a task before the request is sent
  console.log('Request was sent');

  return config;
}, error => {
  // handle the error
  return Promise.reject(error);
});

// sent a GET request
axios.get('https://api.github.com/users/mapbox')
  .then(response => {
    console.log(response.data.created_at);
  });

This code logs a message to the console whenever a request is sent then waits until it gets a response from the server, at which point it prints the time the account was created at GitHub to the console. One advantage of using interceptors is that you no longer have to implement tasks for each HTTP request separately.

Axios also provides a response interceptor, which allows you to transform the responses from a server on their way back to the application:

// declare a response interceptor
axios.interceptors.response.use((response) => {
  // do something with the response data
  console.log('Response was received');

  return response;
}, error => {
  // handle the response error
  return Promise.reject(error);
});

// sent a GET request
axios.get('https://api.github.com/users/mapbox')
  .then(response => {
    console.log(response.data.created_at);
  });

Client-side support for protection against XSRF

Cross-site request forgery (or XSRF for short) is a method of attacking a web-hosted app in which the attacker disguises himself as a legal and trusted user to influence the interaction between the app and the user’s browser. There are many ways to execute such an attack, including XMLHttpRequest.

Fortunately, Axios is designed to protect against XSRF by allowing you to embed additional authentication data when making requests. This enables the server to discover requests from unauthorized locations. Here’s how this can be done with Axios:

const options = {
  method: 'post',
  url: '/login',
  xsrfCookieName: 'XSRF-TOKEN',
  xsrfHeaderName: 'X-XSRF-TOKEN',
};

// send the request
axios(options);

While Axios has some features for debugging requests and responses, making sure Axios continues to serve resources to your app in production is where things get tougher. If you’re interested in ensuring requests to the backend or 3rd party services are successful, try LogRocket. [

LogRocket is like a DVR for web apps, recording literally everything that happens on your site. Instead of guessing why problems happen, you can aggregate and report on problematic Axios requests to quickly understand the root cause.

LogRocket instruments your app to record baseline performance timings such as page load time, time to first byte, and slow network requests as well as logs Redux, NgRx. and Vuex actions/state. Start monitoring for free.

Monitoring POST request progress

Another interesting feature of Axios is the ability to monitor request progress. This is especially useful when downloading or uploading large files. The provided example in the Axios documentation gives you a good idea of how that can be done. But for the sake of simplicity and style, we are going to use the Axios Progress Bar module in this tutorial.

The first thing we need to do to use this module is to include the related style and script:

<link rel="stylesheet" type="text/css" href="https://cdn.rawgit.com/rikmms/progress-bar-4-axios/0a3acf92/dist/nprogress.css" />

<script src="https://cdn.rawgit.com/rikmms/progress-bar-4-axios/0a3acf92/dist/index.js"></script>

Then we can implement the progress bar like this:

loadProgressBar()

const url = 'https://media.giphy.com/media/C6JQPEUsZUyVq/giphy.gif';

function downloadFile(url) {
  axios.get(url)
  .then(response => {
    console.log(response)
  })
  .catch(error => {
    console.log(error)
  })
}

downloadFile(url);

To change the default styling of the progress bar, we can override the following style rules:

#nprogress .bar {
    background: red !important;
}

#nprogress .peg {
    box-shadow: 0 0 10px red, 0 0 5px red !important;
}

#nprogress .spinner-icon {
    border-top-color: red !important;
    border-left-color: red !important;
}

Canceling requests

In some situations, you may no longer care about the result and want to cancel a request that’s already sent. This can be done by using a cancel token. The ability to cancel requests was added to Axios in version 1.5 and is based on the cancelable promises proposal. Here’s a simple example:

const source = axios.CancelToken.source();

axios.get('https://media.giphy.com/media/C6JQPEUsZUyVq/giphy.gif', {
  cancelToken: source.token
}).catch(thrown => {
  if (axios.isCancel(thrown)) {
    console.log(thrown.message);
  } else {
    // handle error
  }
});

// cancel the request (the message parameter is optional)
source.cancel('Request canceled.');

You can also create a cancel token by passing an executor function to the CancelToken constructor, as shown below:

const CancelToken = axios.CancelToken;
let cancel;

axios.get('https://media.giphy.com/media/C6JQPEUsZUyVq/giphy.gif', {
  // specify a cancel token
  cancelToken: new CancelToken(c => {
    // this function will receive a cancel function as a parameter
    cancel = c;
  })
}).catch(thrown => {
  if (axios.isCancel(thrown)) {
    console.log(thrown.message);
  } else {
    // handle error
  }
});

// cancel the request
cancel('Request canceled.');

Libraries

Axios’ rise in popularity among developers has resulted in a rich selection of third-party libraries that extend its functionality. From testers to loggers, there’s a library for almost any additional feature you may need when using Axios. Here are some popular libraries currently available:

• axios-vcr: 📼 Record and replay requests in JavaScript
• axios-response-logger: 📣 Axios interceptor which logs responses
• axios-method-override: ⛵️ Axios request method override plugin
• axios-extensions: 🍱 Axios extensions lib, including throttle and cache GET request features
• axios-api-versioning: Add easy-to-manage API versioning to Axios
• axios-cache-plugin: Helps you cache GET requests when using Axios
• axios-cookiejar-support: Add tough-cookie support to Axios
• react-hooks-axios: Custom React Hooks for Axios
• moxios: Mock Axios requests for testing
• redux-saga-requests: Redux-Saga add-on to simplify handling of AJAX requests
• axios-fetch: A Web API Fetch implementation backed by an Axios client
• axios-curlirize: Log any Axios request as a curl command in the console
• axios-actions: Bundle endpoints as callable, reusable services
• mocha-axios: HTTP assertions for Mocha using Axios
• axios-mock-adapter: Axios adapter that allows you to easily mock requests
• axios-debug-log: Axios interceptor of logging request and response with debug library
• redux-axios-middleware: Redux middleware for fetching data with Axios HTTP client
• axiosist: Axios-based supertest: convert nNode.js request handler to Axios adapter, used for Node.js server unit test

#Axios #programming #HTTP #HTTP requests

Axios: Promise Based HTTP Client for The Browser and Node.js

Axios

Promise based HTTP client for the browser and node.js

---

Features

• Make XMLHttpRequests from the browser
• Make http requests from node.js
• Supports the Promise API
• Intercept request and response
• Transform request and response data
• Cancel requests
• Automatic transforms for JSON data
• 🆕 Automatic data object serialization to multipart/form-data and x-www-form-urlencoded body encodings
• Client side support for protecting against XSRF

Browser Support

Latest ✔	Latest ✔	Latest ✔	Latest ✔	Latest ✔	11 ✔

Installing

Using npm:

$ npm install axios

Using bower:

$ bower install axios

Using yarn:

$ yarn add axios

Using pnpm:

$ pnpm add axios

Using jsDelivr CDN:

<script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script>

Using unpkg CDN:

<script src="https://unpkg.com/axios/dist/axios.min.js"></script>

Example

note: CommonJS usage

In order to gain the TypeScript typings (for intellisense / autocomplete) while using CommonJS imports with require() use the following approach:

const axios = require('axios').default;

// axios.<method> will now provide autocomplete and parameter typings

Performing a GET request

const axios = require('axios').default;

// Make a request for a user with a given ID
axios.get('/user?ID=12345')
  .then(function (response) {
    // handle success
    console.log(response);
  })
  .catch(function (error) {
    // handle error
    console.log(error);
  })
  .then(function () {
    // always executed
  });

// Optionally the request above could also be done as
axios.get('/user', {
    params: {
      ID: 12345
    }
  })
  .then(function (response) {
    console.log(response);
  })
  .catch(function (error) {
    console.log(error);
  })
  .then(function () {
    // always executed
  });  

// Want to use async/await? Add the `async` keyword to your outer function/method.
async function getUser() {
  try {
    const response = await axios.get('/user?ID=12345');
    console.log(response);
  } catch (error) {
    console.error(error);
  }
}

NOTE: async/await is part of ECMAScript 2017 and is not supported in Internet Explorer and older browsers, so use with caution.

Performing a POST request

axios.post('/user', {
    firstName: 'Fred',
    lastName: 'Flintstone'
  })
  .then(function (response) {
    console.log(response);
  })
  .catch(function (error) {
    console.log(error);
  });

Performing multiple concurrent requests

function getUserAccount() {
  return axios.get('/user/12345');
}

function getUserPermissions() {
  return axios.get('/user/12345/permissions');
}

Promise.all([getUserAccount(), getUserPermissions()])
  .then(function (results) {
    const acct = results[0];
    const perm = results[1];
  });

axios API

Requests can be made by passing the relevant config to axios.

axios(config)

// Send a POST request
axios({
  method: 'post',
  url: '/user/12345',
  data: {
    firstName: 'Fred',
    lastName: 'Flintstone'
  }
});

// GET request for remote image in node.js
axios({
  method: 'get',
  url: 'https://bit.ly/2mTM3nY',
  responseType: 'stream'
})
  .then(function (response) {
    response.data.pipe(fs.createWriteStream('ada_lovelace.jpg'))
  });

axios(url[, config])

// Send a GET request (default method)
axios('/user/12345');

Request method aliases

For convenience, aliases have been provided for all common request methods.

axios.request(config)

axios.get(url[, config])

axios.delete(url[, config])

axios.head(url[, config])

axios.options(url[, config])

axios.post(url[, data[, config]])

axios.put(url[, data[, config]])

axios.patch(url[, data[, config]])

NOTE

When using the alias methods url, method, and data properties don't need to be specified in config.

Concurrency (Deprecated)

Please use Promise.all to replace the below functions.

Helper functions for dealing with concurrent requests.

axios.all(iterable) axios.spread(callback)

Creating an instance

You can create a new instance of axios with a custom config.

axios.create([config])

const instance = axios.create({
  baseURL: 'https://some-domain.com/api/',
  timeout: 1000,
  headers: {'X-Custom-Header': 'foobar'}
});

Instance methods

The available instance methods are listed below. The specified config will be merged with the instance config.

axios#request(config)

axios#get(url[, config])

axios#delete(url[, config])

axios#head(url[, config])

axios#options(url[, config])

axios#post(url[, data[, config]])

axios#put(url[, data[, config]])

axios#patch(url[, data[, config]])

axios#getUri([config])

Request Config

These are the available config options for making requests. Only the url is required. Requests will default to GET if method is not specified.

{
  // `url` is the server URL that will be used for the request
  url: '/user',

  // `method` is the request method to be used when making the request
  method: 'get', // default

  // `baseURL` will be prepended to `url` unless `url` is absolute.
  // It can be convenient to set `baseURL` for an instance of axios to pass relative URLs
  // to methods of that instance.
  baseURL: 'https://some-domain.com/api/',

  // `transformRequest` allows changes to the request data before it is sent to the server
  // This is only applicable for request methods 'PUT', 'POST', 'PATCH' and 'DELETE'
  // The last function in the array must return a string or an instance of Buffer, ArrayBuffer,
  // FormData or Stream
  // You may modify the headers object.
  transformRequest: [function (data, headers) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `transformResponse` allows changes to the response data to be made before
  // it is passed to then/catch
  transformResponse: [function (data) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `headers` are custom headers to be sent
  headers: {'X-Requested-With': 'XMLHttpRequest'},

  // `params` are the URL parameters to be sent with the request
  // Must be a plain object or a URLSearchParams object
  params: {
    ID: 12345
  },

  // `paramsSerializer` is an optional config in charge of serializing `params`
  paramsSerializer: {
    indexes: null // array indexes format (null - no brackets, false - empty brackets, true - brackets with indexes)
  },

  // `data` is the data to be sent as the request body
  // Only applicable for request methods 'PUT', 'POST', 'DELETE , and 'PATCH'
  // When no `transformRequest` is set, must be of one of the following types:
  // - string, plain object, ArrayBuffer, ArrayBufferView, URLSearchParams
  // - Browser only: FormData, File, Blob
  // - Node only: Stream, Buffer
  data: {
    firstName: 'Fred'
  },
  
  // syntax alternative to send data into the body
  // method post
  // only the value is sent, not the key
  data: 'Country=Brasil&City=Belo Horizonte',

  // `timeout` specifies the number of milliseconds before the request times out.
  // If the request takes longer than `timeout`, the request will be aborted.
  timeout: 1000, // default is `0` (no timeout)

  // `withCredentials` indicates whether or not cross-site Access-Control requests
  // should be made using credentials
  withCredentials: false, // default

  // `adapter` allows custom handling of requests which makes testing easier.
  // Return a promise and supply a valid response (see lib/adapters/README.md).
  adapter: function (config) {
    /* ... */
  },

  // `auth` indicates that HTTP Basic auth should be used, and supplies credentials.
  // This will set an `Authorization` header, overwriting any existing
  // `Authorization` custom headers you have set using `headers`.
  // Please note that only HTTP Basic auth is configurable through this parameter.
  // For Bearer tokens and such, use `Authorization` custom headers instead.
  auth: {
    username: 'janedoe',
    password: 's00pers3cret'
  },

  // `responseType` indicates the type of data that the server will respond with
  // options are: 'arraybuffer', 'document', 'json', 'text', 'stream'
  //   browser only: 'blob'
  responseType: 'json', // default

  // `responseEncoding` indicates encoding to use for decoding responses (Node.js only)
  // Note: Ignored for `responseType` of 'stream' or client-side requests
  responseEncoding: 'utf8', // default

  // `xsrfCookieName` is the name of the cookie to use as a value for xsrf token
  xsrfCookieName: 'XSRF-TOKEN', // default

  // `xsrfHeaderName` is the name of the http header that carries the xsrf token value
  xsrfHeaderName: 'X-XSRF-TOKEN', // default

  // `onUploadProgress` allows handling of progress events for uploads
  // browser only
  onUploadProgress: function (progressEvent) {
    // Do whatever you want with the native progress event
  },

  // `onDownloadProgress` allows handling of progress events for downloads
  // browser only
  onDownloadProgress: function (progressEvent) {
    // Do whatever you want with the native progress event
  },

  // `maxContentLength` defines the max size of the http response content in bytes allowed in node.js
  maxContentLength: 2000,

  // `maxBodyLength` (Node only option) defines the max size of the http request content in bytes allowed
  maxBodyLength: 2000,

  // `validateStatus` defines whether to resolve or reject the promise for a given
  // HTTP response status code. If `validateStatus` returns `true` (or is set to `null`
  // or `undefined`), the promise will be resolved; otherwise, the promise will be
  // rejected.
  validateStatus: function (status) {
    return status >= 200 && status < 300; // default
  },

  // `maxRedirects` defines the maximum number of redirects to follow in node.js.
  // If set to 0, no redirects will be followed.
  maxRedirects: 21, // default

  // `beforeRedirect` defines a function that will be called before redirect.
  // Use this to adjust the request options upon redirecting,
  // to inspect the latest response headers,
  // or to cancel the request by throwing an error
  // If maxRedirects is set to 0, `beforeRedirect` is not used.
  beforeRedirect: (options, { headers }) => {
    if (options.hostname === "example.com") {
      options.auth = "user:password";
    }
  },

  // `socketPath` defines a UNIX Socket to be used in node.js.
  // e.g. '/var/run/docker.sock' to send requests to the docker daemon.
  // Only either `socketPath` or `proxy` can be specified.
  // If both are specified, `socketPath` is used.
  socketPath: null, // default

  // `httpAgent` and `httpsAgent` define a custom agent to be used when performing http
  // and https requests, respectively, in node.js. This allows options to be added like
  // `keepAlive` that are not enabled by default.
  httpAgent: new http.Agent({ keepAlive: true }),
  httpsAgent: new https.Agent({ keepAlive: true }),

  // `proxy` defines the hostname, port, and protocol of the proxy server.
  // You can also define your proxy using the conventional `http_proxy` and
  // `https_proxy` environment variables. If you are using environment variables
  // for your proxy configuration, you can also define a `no_proxy` environment
  // variable as a comma-separated list of domains that should not be proxied.
  // Use `false` to disable proxies, ignoring environment variables.
  // `auth` indicates that HTTP Basic auth should be used to connect to the proxy, and
  // supplies credentials.
  // This will set an `Proxy-Authorization` header, overwriting any existing
  // `Proxy-Authorization` custom headers you have set using `headers`.
  // If the proxy server uses HTTPS, then you must set the protocol to `https`. 
  proxy: {
    protocol: 'https',
    host: '127.0.0.1',
    port: 9000,
    auth: {
      username: 'mikeymike',
      password: 'rapunz3l'
    }
  },

  // `cancelToken` specifies a cancel token that can be used to cancel the request
  // (see Cancellation section below for details)
  cancelToken: new CancelToken(function (cancel) {
  }),

  // an alternative way to cancel Axios requests using AbortController
  signal: new AbortController().signal,

  // `decompress` indicates whether or not the response body should be decompressed 
  // automatically. If set to `true` will also remove the 'content-encoding' header 
  // from the responses objects of all decompressed responses
  // - Node only (XHR cannot turn off decompression)
  decompress: true // default

  // `insecureHTTPParser` boolean.
  // Indicates where to use an insecure HTTP parser that accepts invalid HTTP headers.
  // This may allow interoperability with non-conformant HTTP implementations.
  // Using the insecure parser should be avoided.
  // see options https://nodejs.org/dist/latest-v12.x/docs/api/http.html#http_http_request_url_options_callback
  // see also https://nodejs.org/en/blog/vulnerability/february-2020-security-releases/#strict-http-header-parsing-none
  insecureHTTPParser: undefined // default

  // transitional options for backward compatibility that may be removed in the newer versions
  transitional: {
    // silent JSON parsing mode
    // `true`  - ignore JSON parsing errors and set response.data to null if parsing failed (old behaviour)
    // `false` - throw SyntaxError if JSON parsing failed (Note: responseType must be set to 'json')
    silentJSONParsing: true, // default value for the current Axios version

    // try to parse the response string as JSON even if `responseType` is not 'json'
    forcedJSONParsing: true,
    
    // throw ETIMEDOUT error instead of generic ECONNABORTED on request timeouts
    clarifyTimeoutError: false,
  },

  env: {
    // The FormData class to be used to automatically serialize the payload into a FormData object
    FormData: window?.FormData || global?.FormData
  },

  formSerializer: {
      visitor: (value, key, path, helpers)=> {}; // custom visitor funaction to serrialize form values
      dots: boolean; // use dots instead of brackets format
      metaTokens: boolean; // keep special endings like {} in parameter key 
      indexes: boolean; // array indexes format null - no brackets, false - empty brackets, true - brackets with indexes
  }
}

Response Schema

The response for a request contains the following information.

{
  // `data` is the response that was provided by the server
  data: {},

  // `status` is the HTTP status code from the server response
  status: 200,

  // `statusText` is the HTTP status message from the server response
  statusText: 'OK',

  // `headers` the HTTP headers that the server responded with
  // All header names are lowercase and can be accessed using the bracket notation.
  // Example: `response.headers['content-type']`
  headers: {},

  // `config` is the config that was provided to `axios` for the request
  config: {},

  // `request` is the request that generated this response
  // It is the last ClientRequest instance in node.js (in redirects)
  // and an XMLHttpRequest instance in the browser
  request: {}
}

When using then, you will receive the response as follows:

axios.get('/user/12345')
  .then(function (response) {
    console.log(response.data);
    console.log(response.status);
    console.log(response.statusText);
    console.log(response.headers);
    console.log(response.config);
  });

When using catch, or passing a rejection callback as second parameter of then, the response will be available through the error object as explained in the Handling Errors section.

Config Defaults

You can specify config defaults that will be applied to every request.

Global axios defaults

axios.defaults.baseURL = 'https://api.example.com';

// Important: If axios is used with multiple domains, the AUTH_TOKEN will be sent to all of them.
// See below for an example using Custom instance defaults instead.
axios.defaults.headers.common['Authorization'] = AUTH_TOKEN;

axios.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';

Custom instance defaults

// Set config defaults when creating the instance
const instance = axios.create({
  baseURL: 'https://api.example.com'
});

// Alter defaults after instance has been created
instance.defaults.headers.common['Authorization'] = AUTH_TOKEN;

Config order of precedence

Config will be merged with an order of precedence. The order is library defaults found in lib/defaults.js, then defaults property of the instance, and finally config argument for the request. The latter will take precedence over the former. Here's an example.

// Create an instance using the config defaults provided by the library
// At this point the timeout config value is `0` as is the default for the library
const instance = axios.create();

// Override timeout default for the library
// Now all requests using this instance will wait 2.5 seconds before timing out
instance.defaults.timeout = 2500;

// Override timeout for this request as it's known to take a long time
instance.get('/longRequest', {
  timeout: 5000
});

Interceptors

You can intercept requests or responses before they are handled by then or catch.

// Add a request interceptor
axios.interceptors.request.use(function (config) {
    // Do something before request is sent
    return config;
  }, function (error) {
    // Do something with request error
    return Promise.reject(error);
  });

// Add a response interceptor
axios.interceptors.response.use(function (response) {
    // Any status code that lie within the range of 2xx cause this function to trigger
    // Do something with response data
    return response;
  }, function (error) {
    // Any status codes that falls outside the range of 2xx cause this function to trigger
    // Do something with response error
    return Promise.reject(error);
  });

If you need to remove an interceptor later you can.

const myInterceptor = axios.interceptors.request.use(function () {/*...*/});
axios.interceptors.request.eject(myInterceptor);

You can also clear all interceptors for requests or responses.

const instance = axios.create();
instance.interceptors.request.use(function () {/*...*/});
instance.interceptors.request.clear(); // Removes interceptors from requests
instance.interceptors.response.use(function () {/*...*/});
instance.interceptors.response.clear(); // Removes interceptors from responses

You can add interceptors to a custom instance of axios.

const instance = axios.create();
instance.interceptors.request.use(function () {/*...*/});

When you add request interceptors, they are presumed to be asynchronous by default. This can cause a delay in the execution of your axios request when the main thread is blocked (a promise is created under the hood for the interceptor and your request gets put on the bottom of the call stack). If your request interceptors are synchronous you can add a flag to the options object that will tell axios to run the code synchronously and avoid any delays in request execution.

axios.interceptors.request.use(function (config) {
  config.headers.test = 'I am only a header!';
  return config;
}, null, { synchronous: true });

If you want to execute a particular interceptor based on a runtime check, you can add a runWhen function to the options object. The interceptor will not be executed if and only if the return of runWhen is false. The function will be called with the config object (don't forget that you can bind your own arguments to it as well.) This can be handy when you have an asynchronous request interceptor that only needs to run at certain times.

function onGetCall(config) {
  return config.method === 'get';
}
axios.interceptors.request.use(function (config) {
  config.headers.test = 'special get headers';
  return config;
}, null, { runWhen: onGetCall });

Multiple Interceptors

Given you add multiple response interceptors and when the response was fulfilled

• then each interceptor is executed
• then they are executed in the order they were added
• then only the last interceptor's result is returned
• then every interceptor receives the result of its predecessor
• and when the fulfillment-interceptor throws
  • then the following fulfillment-interceptor is not called
  • then the following rejection-interceptor is called
  • once caught, another following fulfill-interceptor is called again (just like in a promise chain).

Read the interceptor tests for seeing all this in code.

Handling Errors

axios.get('/user/12345')
  .catch(function (error) {
    if (error.response) {
      // The request was made and the server responded with a status code
      // that falls out of the range of 2xx
      console.log(error.response.data);
      console.log(error.response.status);
      console.log(error.response.headers);
    } else if (error.request) {
      // The request was made but no response was received
      // `error.request` is an instance of XMLHttpRequest in the browser and an instance of
      // http.ClientRequest in node.js
      console.log(error.request);
    } else {
      // Something happened in setting up the request that triggered an Error
      console.log('Error', error.message);
    }
    console.log(error.config);
  });

Using the validateStatus config option, you can define HTTP code(s) that should throw an error.

axios.get('/user/12345', {
  validateStatus: function (status) {
    return status < 500; // Resolve only if the status code is less than 500
  }
})

Using toJSON you get an object with more information about the HTTP error.

axios.get('/user/12345')
  .catch(function (error) {
    console.log(error.toJSON());
  });

Cancellation

AbortController

Starting from v0.22.0 Axios supports AbortController to cancel requests in fetch API way:

const controller = new AbortController();

axios.get('/foo/bar', {
   signal: controller.signal
}).then(function(response) {
   //...
});
// cancel the request
controller.abort()

CancelToken 👎deprecated

You can also cancel a request using a CancelToken.

The axios cancel token API is based on the withdrawn cancelable promises proposal.

This API is deprecated since v0.22.0 and shouldn't be used in new projects

You can create a cancel token using the CancelToken.source factory as shown below:

const CancelToken = axios.CancelToken;
const source = CancelToken.source();

axios.get('/user/12345', {
  cancelToken: source.token
}).catch(function (thrown) {
  if (axios.isCancel(thrown)) {
    console.log('Request canceled', thrown.message);
  } else {
    // handle error
  }
});

axios.post('/user/12345', {
  name: 'new name'
}, {
  cancelToken: source.token
})

// cancel the request (the message parameter is optional)
source.cancel('Operation canceled by the user.');

You can also create a cancel token by passing an executor function to the CancelToken constructor:

const CancelToken = axios.CancelToken;
let cancel;

axios.get('/user/12345', {
  cancelToken: new CancelToken(function executor(c) {
    // An executor function receives a cancel function as a parameter
    cancel = c;
  })
});

// cancel the request
cancel();

Note: you can cancel several requests with the same cancel token/abort controller. If a cancellation token is already cancelled at the moment of starting an Axios request, then the request is cancelled immediately, without any attempts to make a real request.

During the transition period, you can use both cancellation APIs, even for the same request:

Using application/x-www-form-urlencoded format

URLSearchParams

By default, axios serializes JavaScript objects to JSON. To send data in the application/x-www-form-urlencoded format instead, you can use the URLSearchParams API, which is supported in the vast majority of browsers, and Node starting with v10 (released in 2018).

const params = new URLSearchParams({ foo: 'bar' });
params.append('extraparam', 'value');
axios.post('/foo', params);

Query string (Older browsers)

For compatibility with very old browsers, there is a polyfill available (make sure to polyfill the global environment).

Alternatively, you can encode data using the qs library:

const qs = require('qs');
axios.post('/foo', qs.stringify({ 'bar': 123 }));

Or in another way (ES6),

import qs from 'qs';
const data = { 'bar': 123 };
const options = {
  method: 'POST',
  headers: { 'content-type': 'application/x-www-form-urlencoded' },
  data: qs.stringify(data),
  url,
};
axios(options);

Older Node.js versions

For older Node.js engines, you can use the querystring module as follows:

const querystring = require('querystring');
axios.post('https://something.com/', querystring.stringify({ foo: 'bar' }));

You can also use the qs library.

NOTE: The qs library is preferable if you need to stringify nested objects, as the querystring method has known issues with that use case.

🆕 Automatic serialization to URLSearchParams

Axios will automatically serialize the data object to urlencoded format if the content-type header is set to "application/x-www-form-urlencoded".

const data = {
  x: 1,
  arr: [1, 2, 3],
  arr2: [1, [2], 3],
  users: [{name: 'Peter', surname: 'Griffin'}, {name: 'Thomas', surname: 'Anderson'}],
};

await axios.postForm('https://postman-echo.com/post', data,
  {headers: {'content-type': 'application/x-www-form-urlencoded'}}
);

The server will handle it as

  {
    x: '1',
    'arr[]': [ '1', '2', '3' ],
    'arr2[0]': '1',
    'arr2[1][0]': '2',
    'arr2[2]': '3',
    'arr3[]': [ '1', '2', '3' ],
    'users[0][name]': 'Peter',
    'users[0][surname]': 'griffin',
    'users[1][name]': 'Thomas',
    'users[1][surname]': 'Anderson'
  }

If your backend body-parser (like body-parser of express.js) supports nested objects decoding, you will get the same object on the server-side automatically

  var app = express();
  
  app.use(bodyParser.urlencoded({ extended: true })); // support encoded bodies
  
  app.post('/', function (req, res, next) {
     // echo body as JSON
     res.send(JSON.stringify(req.body));
  });

  server = app.listen(3000);

Using multipart/form-data format

FormData

To send the data as a multipart/formdata you need to pass a formData instance as a payload. Setting the Content-Type header is not required as Axios guesses it based on the payload type.

const formData = new FormData();
formData.append('foo', 'bar');

axios.post('https://httpbin.org/post', formData);

In node.js, you can use the form-data library as follows:

const FormData = require('form-data');
 
const form = new FormData();
form.append('my_field', 'my value');
form.append('my_buffer', new Buffer(10));
form.append('my_file', fs.createReadStream('/foo/bar.jpg'));

axios.post('https://example.com', form)

🆕 Automatic serialization to FormData

Starting from v0.27.0, Axios supports automatic object serialization to a FormData object if the request Content-Type header is set to multipart/form-data.

The following request will submit the data in a FormData format (Browser & Node.js):

import axios from 'axios';

axios.post('https://httpbin.org/post', {x: 1}, {
  headers: {
    'Content-Type': 'multipart/form-data'
  }
}).then(({data})=> console.log(data));

In the node.js build, the (form-data) polyfill is used by default.

You can overload the FormData class by setting the env.FormData config variable, but you probably won't need it in most cases:

const axios= require('axios');
var FormData = require('form-data');

axios.post('https://httpbin.org/post', {x: 1, buf: new Buffer(10)}, {
  headers: {
    'Content-Type': 'multipart/form-data'
  }
}).then(({data})=> console.log(data));

Axios FormData serializer supports some special endings to perform the following operations:

• {} - serialize the value with JSON.stringify
• [] - unwrap the array-like object as separate fields with the same key

NOTE: unwrap/expand operation will be used by default on arrays and FileList objects

FormData serializer supports additional options via config.formSerializer: object property to handle rare cases:

visitor: Function - user-defined visitor function that will be called recursively to serialize the data object to a FormData object by following custom rules.

dots: boolean = false - use dot notation instead of brackets to serialize arrays and objects;

metaTokens: boolean = true - add the special ending (e.g user{}: '{"name": "John"}') in the FormData key. The back-end body-parser could potentially use this meta-information to automatically parse the value as JSON.

indexes: null|false|true = false - controls how indexes will be added to unwrapped keys of flat array-like objects

• null - don't add brackets (arr: 1, arr: 2, arr: 3)
• false(default) - add empty brackets (arr[]: 1, arr[]: 2, arr[]: 3)
• true - add brackets with indexes (arr[0]: 1, arr[1]: 2, arr[2]: 3)

Let's say we have an object like this one:

const obj = {
  x: 1,
  arr: [1, 2, 3],
  arr2: [1, [2], 3],
  users: [{name: 'Peter', surname: 'Griffin'}, {name: 'Thomas', surname: 'Anderson'}],
  'obj2{}': [{x:1}]
};

The following steps will be executed by the Axios serializer internally:

const formData= new FormData();
formData.append('x', '1');
formData.append('arr[]', '1');
formData.append('arr[]', '2');
formData.append('arr[]', '3');
formData.append('arr2[0]', '1');
formData.append('arr2[1][0]', '2');
formData.append('arr2[2]', '3');
formData.append('users[0][name]', 'Peter');
formData.append('users[0][surname]', 'Griffin');
formData.append('users[1][name]', 'Thomas');
formData.append('users[1][surname]', 'Anderson');
formData.append('obj2{}', '[{"x":1}]');

Axios supports the following shortcut methods: postForm, putForm, patchForm which are just the corresponding http methods with the Content-Type header preset to multipart/form-data.

Files Posting

You can easily sumbit a single file

await axios.postForm('https://httpbin.org/post', {
  'myVar' : 'foo',
  'file': document.querySelector('#fileInput').files[0] 
});

or multiple files as multipart/form-data.

await axios.postForm('https://httpbin.org/post', {
  'files[]': document.querySelector('#fileInput').files 
});

FileList object can be passed directly:

await axios.postForm('https://httpbin.org/post', document.querySelector('#fileInput').files)

All files will be sent with the same field names: files[].

🆕 HTML Form Posting (browser)

Pass HTML Form element as a payload to submit it as multipart/form-data content.

await axios.postForm('https://httpbin.org/post', document.querySelector('#htmlForm'));

FormData and HTMLForm objects can also be posted as JSON by explicitly setting the Content-Type header to application/json:

await axios.post('https://httpbin.org/post', document.querySelector('#htmlForm'), {
  headers: {
    'Content-Type': 'application/json'
  }
})

For example, the Form

<form id="form">
  <input type="text" name="foo" value="1">
  <input type="text" name="deep.prop" value="2">
  <input type="text" name="deep prop spaced" value="3">
  <input type="text" name="baz" value="4">
  <input type="text" name="baz" value="5">

  <select name="user.age">
    <option value="value1">Value 1</option>
    <option value="value2" selected>Value 2</option>
    <option value="value3">Value 3</option>
  </select>

  <input type="submit" value="Save">
</form>

will be submitted as the following JSON object:

{
  "foo": "1",
  "deep": {
    "prop": {
      "spaced": "3"
    }
  },
  "baz": [
    "4",
    "5"
  ],
  "user": {
    "age": "value2"
  }
}

Sending Blobs/Files as JSON (base64) is not currently supported.

Semver

Until axios reaches a 1.0 release, breaking changes will be released with a new minor version. For example 0.5.1, and 0.5.4 will have the same API, but 0.6.0 will have breaking changes.

Promises

axios depends on a native ES6 Promise implementation to be supported. If your environment doesn't support ES6 Promises, you can polyfill.

TypeScript

axios includes TypeScript definitions and a type guard for axios errors.

let user: User = null;
try {
  const { data } = await axios.get('/user?ID=12345');
  user = data.userDetails;
} catch (error) {
  if (axios.isAxiosError(error)) {
    handleAxiosError(error);
  } else {
    handleUnexpectedError(error);
  }
}

Online one-click setup

You can use Gitpod, an online IDE(which is free for Open Source) for contributing or running the examples online.

Resources

• Changelog
• Upgrade Guide
• Ecosystem
• Contributing Guide
• Code of Conduct

Credits

axios is heavily inspired by the $http service provided in AngularJS. Ultimately axios is an effort to provide a standalone $http-like service for use outside of AngularJS.

---

Website • Documentation

---

Download Details:

Author: axios
Source Code: https://github.com/axios/axios 
License: MIT license

#node #javascript #client 

Promise.allSettled() vs Promise.all()

Promise.allSetlled() is recently introduced in ECMA 2020.
Check out how it is different from Promise.all()

https://www.geekstutorialpoint.com/2020/05/promiseallsettled-vs-promiseall.html

#javascript #promise.all #promise.allsettled #ecma #promise #jquery