How axios makes HTTP request client based on Promise

This time I will show you how axios uses Promise-based HTTP request client. What are the precautions for axios Promise-based HTTP request client? The following is a practical case, let's take a look.

axios

Promise-based HTTP request client, which can be used in the browser and node.js at the same time

Features

Send XMLHttpRequests requests in the browser

Send http requests in node.js

Support PromiseAPI

Intercept requests and responses

Convert requests and Response data

Automatic conversion of JSON data

Client support to protect security from XSRF attacks

Browser support

Installation

Use bower:

$ bower install axios

Using npm:

$ npm install axios

Example

Send a GET request

// Make a request for a user with a given IDaxios.get('/user?ID=12345').then(function(response){console.log(response);}).catch(function(response){console.log(response);});
// Optionally the request above could also be done asaxios.get('/user',{params:{ID:12345}}).then(function(response){console.log(response);}).catch(function(response){console.log(response);});

Send a

POST request

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

Send multiple concurrent requests

functiongetUserAccount(){returnaxios.get('/user/12345');}functiongetUserPermissions(){returnaxios.get('/user/12345/permissions');}axios.all([getUserAccount(),getUserPermissions()]).then(axios.spread(function(acct,perms){// Both requests are now complete}));

axios API

You can customize the request by passing the corresponding parameters to axios:

axios(config)
// Send a POST requestaxios({method:'post',url:'/user/12345',data:{firstName:'Fred',lastName:'Flintstone'}});
axios(url[, config])
// Sned a GET request (default method)axios('/user/12345');

Request methodAlias

For convenience, we provide aliases for all supported request methods

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

Note

When using the alias method, the url , method and data attributes do not need to be specified in the config parameters.

Concurrency

Helper methods for handling concurrent requests

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

Create an instance

You can create a new axios instance with custom configuration.

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

Instance methods

All available instance methods are listed below, and the specified configuration will be merged with the configuration of the instance.

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

Request configuration

The following are the available request configuration items, only the url is required. If method is not specified, the default request method is GET.

{// `url` is the server URL that will be used for the requesturl:'/user',
// `method` is the request method to be used when making the requestmethod:'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:' 
// `transformRequest` allows changes to the request data before it is sent to the server
// This is only applicable for request methods 'PUT', 'POST', and 'PATCH'
// The last function in the array must return a string or an ArrayBuffertransformRequest:[function(data){
// Do whatever you want to transform the datareturndata;}],
// `transformResponse` allows changes to the response data to be made before
// it is passed to then/catchtransformResponse:[function(data){
// Do whatever you want to transform the datareturndata;}],
// `headers` are custom headers to be sentheaders:{'X-Requested-With':'XMLHttpRequest'},
// `params` are the URL parameters to be sent with the requestparams:{ID:12345},
// `paramsSerializer` is an optional function in charge of serializing `params`
// (e.g. https://www.npmjs.com/package/qs,  paramsSerializer:function(params){returnQs.stringify(params,{arrayFormat:'brackets'})},
// `data` is the data to be sent as the request body// Only applicable for request methods 'PUT', 'POST', and 'PATCH'
// When no `transformRequest` is set, must be a string, an ArrayBuffer or a hashdata:{firstName:'Fred'},
// `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,
// `withCredentials` indicates whether or not cross-site Access-Control requests
// should be made using credentialswithCredentials:false,
// default// `adapter` allows custom handling of requests which makes testing easier.
// Call `resolve` or `reject` and supply a valid response (see [response docs](#response-api)).adapter:function(resolve,reject,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`.auth:{username:'janedoe',password:'s00pers3cret'}
// `responseType` indicates the type of data that the server will respond with
// options are 'arraybuffer', 'blob', 'document', 'json', 'text'responseType:'json',
// default// `xsrfCookieName` is the name of the cookie to use as a value for xsrf tokenxsrfCookieName:'XSRF-TOKEN',
// default// `xsrfHeaderName` is the name of the http header that carries the xsrf token valuexsrfHeaderName:'X-XSRF-TOKEN',
// default// `progress` allows handling of progress events for 'POST' and 'PUT uploads'
// as well as 'GET' downloadsprogress:function(progressEvent){
// Do whatever you want with the native progress event}}

Response data structure

The response data includes the following information:

{// `data` is the response that was provided by the serverdata:{},
// `status` is the HTTP status code from the server responsestatus:200,
// `statusText` is the HTTP status message from the server responsestatusText:'OK',
// `headers` the headers that the server responded withheaders:{},
// `config` is the config that was provided to `axios` for the requestconfig:{}}

When using then or catch, you will receive the following response:

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);});

Default configuration

You can specify the default configuration for each request.

Global axios default configuration

axios.defaults.baseURL='https:
//api.example.com';axios.defaults.headers.common['Authorization']=AUTH_TOKEN;axios.defaults.headers.post['Content-Type']='application/x-www-form-urlencoded';

Customized instance default configuration

// Set config defaults when creating the instancevarinstance=axios.create({baseURL:' 
// Alter defaults after instance has been createdinstance.defaults.headers.common['Authorization']=AUTH_TOKEN;

Priority order of configuration

Config will be merged with an order of precedence. The order is library defaults found inlib
/defaults.js, thendefaultsproperty of the instance, and finallyconfigargument 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 libraryvarinstance=axios.create();
// Override timeout default for the library
// Now all requests will wait 2.5 seconds before timing outinstance.defaults.timeout=2500;
// Override timeout for this request as it's known to take a long timeinstance.get('/longRequest',{timeout:5000});

Interceptor

You can Intercept requests and responses before processing then or catch

// 添加一个请求拦截器axios.interceptors.request.use(function(config){
// Do something before request is sentreturnconfig;},function(error){
// Do something with request errorreturnPromise.reject(error);});
// 添加一个响应拦截器axios.interceptors.response.use(function(response){
// Do something with response datareturnresponse;},function(error){
// Do something with response errorreturnPromise.reject(error);});

Remove an interceptor:

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

You can add an interceptor to a custom axios instance:

varinstance=axios.create();instance.interceptors.request.use(function(){/*...*/});
错误处理
axios.get('/user/12345').catch(function(response){if(responseinstanceofError){
// Something happened in setting up the request that triggered an Errorconsole.log('Error',response.message);}else{
// The request was made, but the server responded with a status code
// that falls out of the range of 2xxconsole.log(response.data);console.log(response.status);console.log(response.headers);console.log(response.config);}});
Promises
axios 依赖一个原生的 ES6 Promise 实现，如果你的浏览器环境不支持 ES6 Promises，你需要引入polyfill
TypeScript
axios 包含一个TypeScript定义
/// import*asaxiosfrom'axios';axios.get('/user?ID=12345');
Credits
axios is heavily inspired by the$http serviceprovided inAngular. Ultimately axios is an effort to provide a standalone$http-like service for use outside of Angular.
License
MIT

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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