Data fetching libraries streamline the process of making HTTP requests and managing server state in web applications. They provide abstractions and utilities that simplify data retrieval, caching, synchronization, and state management, allowing developers to focus on building features rather than handling the complexities of data fetching. These libraries are essential for improving application performance, user experience, and maintainability by efficiently managing data flow between the client and server.
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axios
60,238,334
106,684
2.14 MB
677
a month ago
MIT
swr
3,427,348
31,342
264 kB
161
a month ago
MIT
react-query
1,369,187
44,725
2.26 MB
115
2 years ago
MIT
@trpc/client
618,339
36,947
350 kB
164
4 days ago
MIT
Feature Comparison: axios vs swr vs react-query vs @trpc/client
Type Safety
axios:
Axios does not provide built-in type safety features. However, you can manually define types for your requests and responses in TypeScript, but this requires additional boilerplate and does not offer the same level of integration as @trpc/client.
swr:
SWR does not provide built-in type safety features. Like React Query, you can use TypeScript to define types for your data, but it requires additional effort to ensure type safety.
react-query:
React Query does not inherently provide type safety but can be used with TypeScript to define types for your data. This requires some manual setup but allows you to maintain type safety in your application.
@trpc/client:
@trpc/client offers full type safety by inferring types from your backend API. This ensures that any changes made to the API are automatically reflected in the client, reducing the chances of runtime errors and improving developer confidence.
Caching Mechanism
axios:
Axios does not provide built-in caching. You would need to implement your own caching logic or use additional libraries to handle caching of requests and responses.
swr:
SWR implements a caching strategy that automatically caches responses and revalidates data in the background. It provides options for configuring revalidation intervals and cache expiration, ensuring that your UI remains up-to-date with minimal overhead.
react-query:
React Query has a powerful caching mechanism that automatically caches responses and allows you to configure cache time, stale time, and background refetching. This helps improve performance by reducing the number of network requests and keeping data fresh.
@trpc/client:
@trpc/client does not implement its own caching mechanism as it relies on the underlying HTTP client. However, it allows you to implement caching strategies at the API level, giving you flexibility in how you manage data.
Data Synchronization
axios:
Axios is a simple HTTP client and does not provide built-in data synchronization features. You would need to manage synchronization logic yourself, which can lead to more complex code if your application requires real-time updates.
swr:
SWR is designed for data synchronization, providing automatic revalidation and background fetching. It keeps your UI in sync with the server by revalidating data when the user focuses on the window or when the network reconnects.
react-query:
React Query excels at data synchronization, automatically refetching data in the background and keeping your UI in sync with the server. It provides hooks for managing data fetching and updating, making it easy to build responsive applications.
@trpc/client:
@trpc/client does not handle data synchronization out of the box, as it focuses on type-safe API calls. You would need to implement synchronization logic manually or use it in conjunction with other libraries.
Learning Curve
axios:
Axios is straightforward to learn and use, making it a good choice for developers who need a simple HTTP client without complex features. Its API is easy to understand, and it integrates well with any JavaScript application.
swr:
SWR is relatively easy to learn, especially for developers familiar with React hooks. Its API is simple and intuitive, allowing you to quickly implement data fetching with minimal setup.
react-query:
React Query has a steeper learning curve due to its rich feature set and concepts like caching and background fetching. However, once mastered, it can greatly simplify data management in React applications.
@trpc/client:
@trpc/client has a moderate learning curve, especially if you are not familiar with TypeScript. However, once you understand its type-safe API calls, it can significantly enhance your development experience.
Extensibility
axios:
Axios is very extensible, providing interceptors for requests and responses, allowing you to modify requests before they are sent or handle responses globally. This makes it easy to implement features like authentication or logging.
swr:
SWR is also extensible, allowing you to create custom fetchers and configure revalidation strategies. This flexibility enables you to tailor data fetching to your specific use case.
react-query:
React Query is extensible through its hooks and configuration options, allowing you to customize caching, refetching, and data synchronization behaviors to suit your application's requirements.
@trpc/client:
@trpc/client is highly extensible, allowing you to customize API calls and integrate with various backends. You can easily extend its functionality to fit your application's needs.
How to Choose: axios vs swr vs react-query vs @trpc/client
axios:
Choose Axios if you need a simple and flexible HTTP client that works in both the browser and Node.js. It provides a rich set of features, including interceptors, request cancellation, and automatic JSON transformation, making it a versatile choice for any JavaScript application.
swr:
Choose SWR if you prefer a lightweight and simple solution for data fetching in React applications that focuses on revalidation and caching. SWR is designed to provide a fast and efficient way to fetch data while keeping your UI in sync with the server.
react-query:
Choose React Query if you want to manage server state in your React applications with powerful caching, synchronization, and background data fetching capabilities. It abstracts away the complexities of data fetching and state management, making it easier to build responsive and performant UIs.
@trpc/client:
Choose @trpc/client if you are using TypeScript and want a type-safe way to call your backend APIs. It integrates seamlessly with your backend, allowing you to infer types directly from your server-side code, which can significantly reduce runtime errors and improve developer productivity.
Similar Npm Packages to axios
axios is a popular promise-based HTTP client for both the browser and Node.js. It simplifies making HTTP requests and handling responses, providing a clean and intuitive API. Axios supports features such as request and response interception, automatic JSON data transformation, and the ability to cancel requests. It is widely used in web applications for interacting with RESTful APIs and is known for its ease of use and flexibility. However, there are several alternatives to axios that developers may consider based on their specific needs:
node-fetch is a lightweight module that brings window.fetch to Node.js. It is a simple and minimalistic implementation of the Fetch API, allowing developers to make HTTP requests using a familiar API. Node-fetch is particularly useful for server-side applications or when working with APIs in a Node.js environment. It supports promises and is a great choice for those who prefer the Fetch API's syntax and behavior over traditional XMLHttpRequest or other libraries.
request was once one of the most popular HTTP request libraries for Node.js. It provided a simple and flexible API for making HTTP requests and handling responses. However, it has been deprecated and is no longer actively maintained. While it may still be found in legacy projects, developers are encouraged to use more modern alternatives like axios or node-fetch for new applications.
superagent is another powerful HTTP request library for Node.js and browsers. It offers a flexible and expressive API for making HTTP requests, supporting features like chaining, automatic content type handling, and file uploads. Superagent is particularly useful for developers who need a more feature-rich alternative to axios or want to work with a library that provides a more expressive syntax.
swr is a data fetching library for React applications that simplifies the process of retrieving and caching data from APIs. It stands for "stale-while-revalidate," which reflects its core functionality of returning cached data while simultaneously revalidating it in the background. This approach enhances user experience by providing instant feedback while ensuring that the data remains fresh. SWR is particularly useful for applications that require frequent data updates, as it handles caching, revalidation, and error handling seamlessly.
While SWR is a powerful tool for data fetching, there are several alternatives that offer similar functionalities. Here are two notable options:
axios-hooks is a library that integrates axios, a popular promise-based HTTP client, with React's hooks. It allows developers to easily make HTTP requests and manage the resulting state within functional components. Axios-hooks provides a simple and intuitive API, making it a great choice for those who are already familiar with axios and prefer a hook-based approach for managing data fetching in their applications.
react-query is another robust data-fetching library for React applications. It offers a comprehensive set of features for managing server-state, including caching, background updates, and synchronization. React-query is designed to handle complex data-fetching scenarios, making it ideal for applications that require advanced capabilities. With its powerful caching and automatic refetching features, react-query can significantly improve the performance and maintainability of your application.
react-query is a powerful data-fetching and state management library for React applications. It simplifies the process of fetching, caching, and synchronizing server state, allowing developers to focus on building their applications without worrying about the complexities of data management. With features like automatic caching, background updates, and query invalidation, react-query is well-suited for applications that rely heavily on server data. It provides a robust solution for managing asynchronous data and is particularly useful in scenarios where data needs to be fetched frequently or updated in real-time.
While react-query is a fantastic choice for data fetching, there are several alternatives worth considering:
axios is a popular promise-based HTTP client for making requests to external APIs. While it is not a state management library itself, it is often used in conjunction with state management solutions to handle data fetching. Developers appreciate axios for its simplicity, ease of use, and ability to intercept requests and responses. If you prefer a straightforward approach to making HTTP requests without the additional features of a data-fetching library, axios is a solid choice.
redux-query is a library that integrates data fetching with Redux, allowing developers to manage server state alongside their application state. It provides a way to define queries and mutations in a Redux-friendly manner, making it easier to manage complex data-fetching scenarios. If your application already uses Redux for state management and you want to incorporate data fetching into that flow, redux-query can be a good fit.
swr is another data-fetching library for React that focuses on simplicity and performance. It provides features such as caching, revalidation, and automatic retries, similar to react-query. swr is designed to work seamlessly with React's hooks, making it a great option for developers looking for a minimalistic approach to data fetching. If you prefer a lightweight library that still offers powerful data-fetching capabilities, swr is worth considering.
@trpc/client is a powerful library designed for building type-safe APIs in TypeScript applications. It allows developers to create and consume APIs with ease, leveraging the benefits of TypeScript for improved developer experience and reduced runtime errors. By using @trpc/client, developers can seamlessly connect to their backend services while enjoying features like automatic type inference and end-to-end type safety. This makes it an excellent choice for applications where type safety and developer productivity are priorities.
While @trpc/client offers a unique approach to API communication, there are several alternatives in the React ecosystem that also facilitate data fetching and state management. Here are a few notable options:
axios is a widely-used promise-based HTTP client for making requests to APIs. It provides a simple and intuitive API for handling requests and responses, along with features like interceptors, request cancellation, and automatic JSON data transformation. If you're looking for a straightforward solution for making HTTP requests without the need for additional abstractions, axios is a solid choice. It is particularly useful for applications that require a robust and flexible HTTP client without the added complexity of a full-fledged data-fetching library.
react-query is a powerful data-fetching library that simplifies the management of server-state in React applications. It provides features like caching, background updates, and automatic retries, making it an excellent choice for applications that require complex data-fetching scenarios. With react-query, developers can focus on building their UI while the library handles the intricacies of data fetching and state management. If your application needs advanced capabilities for managing server-state, react-query is a great option.
swr is another data-fetching library that emphasizes simplicity and efficiency. It allows developers to fetch, cache, and update data seamlessly in React applications. With features like revalidation and automatic caching, swr provides a lightweight solution for managing remote data. If you prefer a minimalistic approach to data fetching that integrates well with React's functional components, swr is worth considering.
For some bundlers and some ES6 linters you may need to do the following:
import { default as axios } from 'axios';
For cases where something went wrong when trying to import a module into a custom or legacy environment,
you can try importing the module package directly:
Note: CommonJS usage
In order to gain the TypeScript typings (for intellisense / autocomplete) while using CommonJS imports with require(), use the following approach:
import axios from 'axios';
//const axios = require('axios'); // legacy way
// 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);
})
.finally(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);
})
.finally(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.
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 and option `allowAbsoluteUrls` is set to true.
// 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/',
// `allowAbsoluteUrls` determines whether or not absolute URLs will override a configured `baseUrl`.
// When set to true (default), absolute values for `url` will override `baseUrl`.
// When set to false, absolute values for `url` will always be prepended by `baseUrl`.
allowAbsoluteUrls: true,
// `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 that allows you to customize serializing `params`.
paramsSerializer: {
// Custom encoder function which sends key/value pairs in an iterative fashion.
encode?: (param: string): string => { /* Do custom operations here and return transformed string */ },
// Custom serializer function for the entire parameter. Allows user to mimic pre 1.x behaviour.
serialize?: (params: Record<string, any>, options?: ParamsSerializerOptions ),
// Configuration for formatting array indexes in the params.
indexes: false // Three available options: (1) indexes: null (leads to no brackets), (2) (default) indexes: false (leads to empty brackets), (3) indexes: true (leads to 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, FormData (form-data package)
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) {
/* ... */
},
// Also, you can set the name of the built-in adapter, or provide an array with their names
// to choose the first available in the environment
adapter: 'xhr', // 'fetch' | 'http' | ['xhr', 'http', 'fetch']
// `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
// options are: 'ascii', 'ASCII', 'ansi', 'ANSI', 'binary', 'BINARY', 'base64', 'BASE64', 'base64url',
// 'BASE64URL', 'hex', 'HEX', 'latin1', 'LATIN1', 'ucs-2', 'UCS-2', 'ucs2', 'UCS2', 'utf-8', 'UTF-8',
// 'utf8', 'UTF8', 'utf16le', 'UTF16LE'
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
// `undefined` (default) - set XSRF header only for the same origin requests
withXSRFToken: boolean | undefined | ((config: InternalAxiosRequestConfig) => boolean | undefined),
// `onUploadProgress` allows handling of progress events for uploads
// browser & node.js
onUploadProgress: function ({loaded, total, progress, bytes, estimated, rate, upload = true}) {
// Do whatever you want with the Axios progress event
},
// `onDownloadProgress` allows handling of progress events for downloads
// browser & node.js
onDownloadProgress: function ({loaded, total, progress, bytes, estimated, rate, download = true}) {
// Do whatever you want with the Axios 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
// `transport` determines the transport method that will be used to make the request.
// If defined, it will be used. Otherwise, if `maxRedirects` is 0,
// the default `http` or `https` library will be used, depending on the protocol specified in `protocol`.
// Otherwise, the `httpFollow` or `httpsFollow` library will be used, again depending on the protocol,
// which can handle redirects.
transport: undefined, // 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',
// hostname: '127.0.0.1' // Takes precedence over 'host' if both are defined
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 function to serialize 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
},
// http adapter only (node.js)
maxRate: [
100 * 1024, // 100KB/s upload limit,
100 * 1024 // 100KB/s download limit
]
}
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:
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/index.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.
const instance = axios.create();
// Add a request interceptor
instance.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
instance.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.
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 request 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.
There are many different axios error messages that can appear that can provide basic information about the specifics of the error and where opportunities may lie in debugging.
The general structure of axios errors is as follows:
| Property | Definition |
| -------- | ---------- |
| message | A quick summary of the error message and the status it failed with. |
| name | This defines where the error originated from. For axios, it will always be an 'AxiosError'. |
| stack | Provides the stack trace of the error. |
| config | An axios config object with specific instance configurations defined by the user from when the request was made |
| code | Represents an axios identified error. The table below lists out specific definitions for internal axios error. |
| status | HTTP response status code. See here for common HTTP response status code meanings.
Below is a list of potential axios identified error:
| Code | Definition |
| -------- | ---------- |
| ERR_BAD_OPTION_VALUE | Invalid or unsupported value provided in axios configuration. |
| ERR_BAD_OPTION | Invalid option provided in axios configuration. |
| ECONNABORTED | Request timed out due to exceeding timeout specified in axios configuration. |
| ETIMEDOUT | Request timed out due to exceeding default axios timelimit. |
| ERR_NETWORK | Network-related issue.
| ERR_FR_TOO_MANY_REDIRECTS | Request is redirected too many times; exceeds max redirects specified in axios configuration.
| ERR_DEPRECATED | Deprecated feature or method used in axios.
| ERR_BAD_RESPONSE | Response cannot be parsed properly or is in an unexpected format.
| ERR_BAD_REQUEST | Requested has unexpected format or missing required parameters. |
| ERR_CANCELED | Feature or method is canceled explicitly by the user.
| ERR_NOT_SUPPORT | Feature or method not supported in the current axios environment.
| ERR_INVALID_URL | Invalid URL provided for axios request.
Handling Errors
the default behavior is to reject every response that returns with a status code that falls out of the range of 2xx and treat it as an error.
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 override the default condition (status >= 200 && status < 300) and 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.
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:
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):
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.
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.
Sending Blobs/Files as JSON (base64) is not currently supported.
🆕 Progress capturing
Axios supports both browser and node environments to capture request upload/download progress.
The frequency of progress events is forced to be limited to 3 times per second.
await axios.post(url, data, {
onUploadProgress: function (axiosProgressEvent) {
/*{
loaded: number;
total?: number;
progress?: number; // in range [0..1]
bytes: number; // how many bytes have been transferred since the last trigger (delta)
estimated?: number; // estimated time in seconds
rate?: number; // upload speed in bytes
upload: true; // upload sign
}*/
},
onDownloadProgress: function (axiosProgressEvent) {
/*{
loaded: number;
total?: number;
progress?: number;
bytes: number;
estimated?: number;
rate?: number; // download speed in bytes
download: true; // download sign
}*/
}
});
You can also track stream upload/download progress in node.js:
Note:
Capturing FormData upload progress is not currently supported in node.js environments.
⚠️ Warning
It is recommended to disable redirects by setting maxRedirects: 0 to upload the stream in the node.js environment,
as follow-redirects package will buffer the entire stream in RAM without following the "backpressure" algorithm.
🆕 Rate limiting
Download and upload rate limits can only be set for the http adapter (node.js):
Axios has its own AxiosHeaders class to manipulate headers using a Map-like API that guarantees caseless work.
Although HTTP is case-insensitive in headers, Axios will retain the case of the original header for stylistic reasons
and for a workaround when servers mistakenly consider the header's case.
The old approach of directly manipulating headers object is still available, but deprecated and not recommended for future usage.
Working with headers
An AxiosHeaders object instance can contain different types of internal values. that control setting and merging logic.
The final headers object with string values is obtained by Axios by calling the toJSON method.
Note: By JSON here we mean an object consisting only of string values intended to be sent over the network.
The header value can be one of the following types:
string - normal string value that will be sent to the server
null - skip header when rendering to JSON
false - skip header when rendering to JSON, additionally indicates that set method must be called with rewrite option set to true
to overwrite this value (Axios uses this internally to allow users to opt out of installing certain headers like User-Agent or Content-Type)
undefined - value is not set
Note: The header value is considered set if it is not equal to undefined.
The headers object is always initialized inside interceptors and transformers:
axios.interceptors.request.use((request: InternalAxiosRequestConfig) => {
request.headers.set('My-header', 'value');
request.headers.set({
"My-set-header1": "my-set-value1",
"My-set-header2": "my-set-value2"
});
request.headers.set('User-Agent', false); // disable subsequent setting the header by Axios
request.headers.setContentType('text/plain');
request.headers['My-set-header2'] = 'newValue' // direct access is deprecated
return request;
}
);
You can iterate over an AxiosHeaders instance using a for...of statement:
const headers = new AxiosHeaders({
foo: '1',
bar: '2',
baz: '3'
});
for(const [header, value] of headers) {
console.log(header, value);
}
// foo 1
// bar 2
// baz 3
Returns the internal value of the header. It can take an extra argument to parse the header's value with RegExp.exec,
matcher function or internal key-value parser.
Returns true if at least one header has been cleared.
AxiosHeaders#normalize(format);
If the headers object was changed directly, it can have duplicates with the same name but in different cases.
This method normalizes the headers object by combining duplicate keys into one.
Axios uses this method internally after calling each interceptor.
Set format to true for converting headers name to lowercase and capitalize the initial letters (cOntEnt-type => Content-Type)
Merges the instance with targets into a new AxiosHeaders instance. If the target is a string, it will be parsed as RAW HTTP headers.
Returns a new AxiosHeaders instance.
AxiosHeaders#toJSON(asStrings?)
toJSON(asStrings?: boolean): RawAxiosHeaders;
Resolve all internal headers values into a new null prototype object.
Set asStrings to true to resolve arrays as a string containing all elements, separated by commas.
Returns a new AxiosHeaders instance created from the raw headers passed in,
or simply returns the given headers object if it's an AxiosHeaders instance.
Fetch adapter was introduced in v1.7.0. By default, it will be used if xhr and http adapters are not available in the build,
or not supported by the environment.
To use it by default, it must be selected explicitly:
The adapter supports the same functionality as xhr adapter, including upload and download progress capturing.
Also, it supports additional response types such as stream and formdata (if supported by the environment).
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);
}
}
Because axios dual publishes with an ESM default export and a CJS module.exports, there are some caveats.
The recommended setting is to use "moduleResolution": "node16" (this is implied by "module": "node16"). Note that this requires TypeScript 4.7 or greater.
If use ESM, your settings should be fine.
If you compile TypeScript to CJS and you can’t use "moduleResolution": "node 16", you have to enable esModuleInterop.
If you use TypeScript to type check CJS JavaScript code, your only option is to use "moduleResolution": "node16".
Online one-click setup
You can use Gitpod, an online IDE(which is free for Open Source) for contributing or running the examples online.
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.