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    RESTful mock server using axios.

    Table of contents


    • You can create a GET/POST/PUT/DELETE API endpoint in a few lines.
    • A dedicated server is not required.
    • It works with SPA as a static JavaScript file.
    • You can use axios as mock-up even in Node.js environment.
    • There is an auto-routing function similar to Nuxt.js, and no path description is required.
    • Supports TypeScript.
    • small func added by sb

    Getting Started


    • Using npm:

      $ npm install axios
      $ npm install axios-mock-server --save-dev
    • Using Yarn:

      $ yarn add axios
      $ yarn add axios-mock-server --dev


    Introducing the simplest use of axios-mock-server.

    Start the tutorial

    Create API

    First, create a mocks directory to store the files you want to mock up.

    $ mkdir mocks

    Next, create an API endpoint file in the mocks directory.
    Let's define a mock API that retrieves basic user information with a GET request.

    Create a mocks/users directory and create a _userId.js file.

    $ mkdir mocks/users
    $ touch mocks/users/_userId.js
    # If Windows (Command Prompt) 
    > mkdir mocks\users
    > echo> mocks\users\_userId.js

    Add the following to the mocks/users/_userId.js file.

    // file: 'mocks/users/_userId.js'
    const users = [{ id: 0, name: 'foo' }, { id: 1, name: 'bar' }]
    module.exports = {
      get({ values }) {
        return [200, users.find(user => === values.userId)]

    The routing of axios-mock-server is automatically generated according to the tree structure of JavaScript and TypeScript files in the mocks directory in the same way as the routing of Nuxt.js.

    Reference: Routing - Nuxt.js

    In other words, the mocks/users/_userId.js file can define an endpoint using dynamic routing as the path of /users/:userId.

    Build API

    axios-mock-server needs to build and generate the necessary files for routing before running.

    $ node_modules/.bin/axios-mock-server
    # If Windows (Command Prompt) 
    > node_modules\.bin\axios-mock-server

    If the build is successful, the $mock.js file is generated in themocks directory.

    $ cat mocks/\$mock.js
    /* eslint-disable */
    module.exports = (client) => require('axios-mock-server')([
        path: '/users/_userId',
        methods: require('./users/_userId')
    ], client)
    # If Windows (Command Prompt) 
    > type mocks\$mock.js

    Mocking Axios

    Finally, import the mocks/$mock.js file generated by index.js file etc. and pass it to the argument of axios-mock-server.
    axios-mock-server will mock up all axios communications by default.

    // file: 'index.js'
    const axios = require('axios')
    const mock = require('./mocks/$mock.js')
    axios.get('').then(({ data }) => {

    If you run the index.js file, you will see that { id: 1, name: 'bar' } is returned.

    $ node index.js
    { id: 1, name: 'bar' }


    axios-mock-server can be used to mock up browser usage, data persistence and multipart/form-data format communication.
    It is also easy to link with Nuxt.js (@nuxtjs/axios).

    See examples for source code.

    See a list of use cases


    • with-in-memory-database


    Create an API endpoint

    const users = [{ id: 0, name: 'foo' }, { id: 1, name: 'bar' }]
     * Type definitions for variables passed as arguments in requests
     * @typedef { Object } MockMethodParams
     * @property { import('axios').AxiosRequestConfig } config axios request settings
     * @property {{ [key: string]: string | number }} values Dynamic value of the requested URL (underscore part of the path)
     * @property {{ [key: string]: any }} params The value of the query parameter for the requested URL
     * @property { any } data Request data sent by POST etc.
     * Type definition when response is returned as an object
     * @typedef { Object } MockResponseObject
     * @property { number } status HTTP response status code
     * @property { any? } data Response data
     * @property {{ [key: string]: any }?} headers Response header
     * Response type definition
     * @typedef { [number, any?, { [key: string]: any }?] | MockResponseObject } MockResponse
    export default {
       * All methods such as GET and POST have the same type
       * @param { MockMethodParams }
       * @returns { MockResponse }
      get({ values }) {
        return [200, users.find(user => === values.userId)]
       * You can also return a response asynchronously
       * @param { MockMethodParams }
       * @returns { Promise<MockResponse> }
      async post({ data }) {
        await new Promise(resolve => setTimeout(resolve, 1000))
          id: users.length,
        return { status: 201 }

    Connect to axios


    axios-mock-server will mock up all axios communications by default.

    import axios from 'axios'
    import mock from './mocks/$mock.js'
    axios.get('').then(response => {
      /* ... */

    Each instance

    You can also mock up each axios instance.

    import axios from 'axios'
    import mock from './mocks/$mock.js'
    const client = axios.create({ baseURL: '' })
    client.get('/foo').then(response => {
      /* ... */
    // axios will not be mocked up
    axios.get('').catch(error => {
      console.log(error.response.status) // 404


    axios-mock-server has several built-in functions available.

    setDelayTime(millisecond: number): void

    Simulate response delay.

    import axios from 'axios'
    import mock from './mocks/$mock.js'
    axios.get('').then(() => {
      console.timeEnd() // default: 506.590ms

    enableLog(): void and disableLog(): void

    Switch request log output.

    import axios from 'axios'
    import mock from './mocks/$mock.js'
    const mockServer = mock()
    ;(async () => {
      // To enable
      await axios.get('/foo', { baseURL: '', params: { bar: 'baz' } }) // stdout -> [mock] get: /foo?bar=baz => 200
      // To disable
      await axios.get('/foo', { baseURL: '', params: { bar: 'baz' } }) // stdout ->


    axios-mock-server includes TypeScript definitions.



    Exclude $mock.js or $mock.ts generated by axios-mock-server in the build from Git monitoring.

    echo "\$mock.*" >> .gitignore
    # If Windows (Command Prompt) 
    > echo $mock.* >> .gitignore

    @ts-ignore, eslint-disable

    For TypeScript projects, add a // @ ts-ignore comment to the above line that imports$ mock.ts. If @typescript-eslint/ban-ts-ignore rule is enabled in typescript-eslint, please exclude the // @ ts-ignore comment from ESLint.

    // eslint-disable-next-line @typescript-eslint/ban-ts-ignore
    // @ts-ignore: Cannot find module
    import mock from './mocks/$mock'


    The expected type comes from property 'get' which is declared here on type 'MockMethods' error in TypeScript

    When returning a response asynchronously with TypeScript, an error occurs because the type does not match if you try to make the response an array.
    Assert MockResponse or return it as an object.

    Example of error (Note that the axios-mock-server build will pass!)

    import { MockMethods } from 'axios-mock-server'
    const methods: MockMethods = {
      async get() {
        await new Promise(resolve => setTimeout(resolve, 100))
        return [200, { foo: 'bar' }] // Error
    export default methods

    Resolve by asserting MockResponse.

    import { MockMethods, MockResponse } from 'axios-mock-server'
    const methods: MockMethods = {
      async get() {
        await new Promise(resolve => setTimeout(resolve, 100))
        return [200, { foo: 'bar' }] as MockResponse // Type safe
    export default methods

    If the response can be an object, no assertion is required.

    import { MockMethods } from 'axios-mock-server'
    const methods: MockMethods = {
      async get() {
        await new Promise(resolve => setTimeout(resolve, 100))
        return { status: 200, data: { foo: 'bar' } } // Type safe
    export default methods

    Command Line Interface Options

    The following options can be specified in the Command Line Interface.

    Option Type Default Description
    string ".mockserverrc" Specify the path to the configuration file.
    Enable watch mode.
    Regenerate $mock.js or $mock.ts according to the increase / decrease of the API endpoint file.
    Print axios-mock-server version.


    Settings are written in .mockserverrc file with JSON syntax.

    Option Type Default Description
    input string | string[] "mocks" or "apis" Specify the directory where the API endpoint file is stored.
    If multiple directories are specified, $mock.js or $mock.ts is generated in each directory.
    outputExt "js" | "ts" Specify the extension of the file to be generated.
    The default is set automatically from scripts of the API endpoint file.
    target "es6" | "cjs" Specify the code of the module to be generated.
    The default is set automatically from extension of the API endpoint file.


    axios-mock-server is licensed under a MIT License.


    npm i sb-axios-mock-server

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