vite-plugin-mock-dev-server
Advanced tools
Vite Plugin for API mock dev server.
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json / json5.mockjs, or do not use it.text/json/buffer/stream.server.proxyviteConfig.define and env in the mock file.viteConfig.resolve.alias in the mock file.vite preview mode.multipart content-type, mock upload file.WebSocket MockSee the documentation to learn more.
# npm
npm i -D vite-plugin-mock-dev-server
# yarn
yarn add vite-plugin-mock-dev-server
# pnpm
pnpm add -D vite-plugin-mock-dev-server
vite.config.ts
import { defineConfig } from 'vite'
import mockDevServerPlugin from 'vite-plugin-mock-dev-server'
export default defineConfig({
plugins: [
mockDevServerPlugin(),
],
// The fields defined here can also be used in mock.
define: {},
server: {
proxy: {
'^/api': { target: 'http://example.com' }
}
}
})
The plugin will read the configuration of server.proxy or options.prefix, and enable mock matching for matched URLs.
The plugin will also read the define configuration, which supports direct use in mock files.
Because in general scenarios, we only need to mock URLs with proxies so that we can use the proxy and mock services provided by Vite's HTTP service.
However, you can also configure mocks using
options.prefix.
By default, write mock data in the mock directory of your project's root directory:
mock/**/*.mock.ts :
import { defineMock } from 'vite-plugin-mock-dev-server'
export default defineMock({
url: '/api/test',
body: { a: 1, b: 2 }
})
Vite plugin
vite.config.ts
import { defineConfig } from 'vite'
import mockDevServerPlugin from 'vite-plugin-mock-dev-server'
export default defineConfig({
plugins: [
mockDevServerPlugin(),
]
})
options.prefix
Type: string | string[]
Configure custom matching rules for the mock server. Any request path starting with the value of prefix will be proxied to the corresponding target. If the prefix value starts with ^, it will be recognized as a RegExp.
In general,
server.proxyis sufficient to meet the needs. Adding this item is for compatibility with certain scenarios.
Default: []
options.wsPrefix
Type: string | string[]
Configure the matching rules for the WebSocket service. Any request path starting with the value of wsPrefix and using the ws/wss protocol will be proxied to the corresponding target.
If the value of wsPrefix starts with ^, it will be recognized as a RegExp.
Different from using
viteConfig.server.proxyby default for http mock,websocket mockdoes not use the ws-related configuration inviteConfig.server.proxy. Also, rules configured inwsPrefixcannot be configured simultaneously inviteConfig.server.proxy, as it will cause conflicts when starting the vite server because multiple instances of WebSocketServer cannot be implemented for the same request. This conflict is neither a problem with Vite nor with the plugin; it belongs to a reasonable error type. When switching between WebSocket Mock and WebSocket Proxy, please pay attention to avoid duplicate configurations that may cause conflicts.
option.cwd
Type: string
Configure the matching context for include and exclude.
Default： process.cwd()
option.include
Type: string | string[]
Configure to read mock files, which can be a directory, glob, or an array.
Default： ['mock/**/*.mock.{js,ts,cjs,mjs,json,json5}'] (Relative to the root directory.)
options.exclude
Type: string | string[]
When reading mock files for configuration, the files that need to be excluded can be a directory, glob, or array.
Default： ['**/node_modules/**','**/.vscode/**','**/.git/**']
options.reload
Type: boolean
When the mock resource is hot updated, only the data content is updated, but the page is not refreshed by default. If you want to refresh the page every time you modify the mock file, you can open this option.
options.cors
Type: boolean | CorsOptions
Enable by default.
Configure to cors, see cors
Default: true
options.log
Type: boolean | 'info' | 'warn' | 'error' | 'silent'
Enable log and configure log level.
options.formidableOptions
Configure to formidable, see formidable options
Default: {}
example: Configure to file upload dir
MockDevServerPlugin({
formidableOptions: {
uploadDir: path.join(process.cwd(), 'uploads'),
}
})
options.cookiesOptions
Configure to cookies, see cookies
Default: {}
options.bodyParserOptions
Configure to co-body, see co-body
Default: {}
options.build
The configuration needed to build a small, independently deployable mock service.
Type： boolean | ServerBuildOptions
Default： false
interface ServerBuildOptions {
/**
* server port
* @default 8080
*/
serverPort?: number
/**
* build output dir
* @default 'mockServer'
*/
dist?: string
/**
* log level
* @default 'error'
*/
log?: LogLevel
}
options.priority
Custom path matching rule priority。read more
Default： undefined
Mock Type Helper
import { defineMock } from 'vite-plugin-mock-dev-server'
export default defineMock({
url: '/api/test',
body: {}
})
Return a custom defineMock function to support preprocessing of mock config.
import path from 'node:path'
import { createDefineMock } from 'vite-plugin-mock-dev-server'
// Preprocessed mock url
const defineAPIMock = createDefineMock((mock) => {
mock.url = path.join('/api', mock.url)
})
export default defineApiMock({
url: '/test' // Complete as '/api/test'
})
// Configure the http mock
export default defineMock({
/**
* Request address, supports the `/api/user/:id` format.
* The plugin matches the path through `path-to-regexp`.
* @see https://github.com/pillarjs/path-to-regexp
*/
url: '/api/test',
/**
* Supported request methods of the interface.
* @type string | string[]
* @default ['POST','GET']
*
*/
method: ['GET', 'POST'],
/**
* In practical scenarios,
* we usually only need certain mock interfaces to take effect,
* rather than enabling all mock interfaces.
* For interfaces that do not currently require mocking,
* they can be set to false.
*
* @default true
*/
enabled: true,
/**
* Set interface response delay, if an array is passed in,
* it represents the range of delay time.
* unit: ms.
* @default 0
*/
delay: 1000,
/**
* response status
* @default 200
*/
status: 200,
/**
* response status text
*/
statusText: 'OK',
/**
* response headers
* @type Record<string, any>
* @type (({ query, body, params, headers }) => Record<string, any>)
*/
headers: {
'Content-Type': 'application/json'
},
/**
* response cookies
* @type Record<string, string | [value: string, option: CookieOption]>
* @see https://github.com/pillarjs/cookies#cookiessetname--values--options
*/
cookies: {
'your-cookie': 'your cookie value',
'cookie&option': ['cookie value', { path: '/', httpOnly: true }]
},
/**
* Response body data type, optional values include `text, json, buffer`.
* And also support types included in `mime-db`.
* When the response body returns a file and you are not sure which type to use,
* you can pass the file name as the value. The plugin will internally search for matching
* `content-type` based on the file name suffix.
* However, if it is a TypeScript file such as `a.ts`, it may not be correctly matched
* as a JavaScript script. You need to modify `a.ts` to `a.js` as the value passed
* in order to recognize it correctly.
* @see https://github.com/jshttp/mime-db
* @default 'json'
*/
type: 'json',
/**
* Response Body
* Support `string/number/array/object/buffer/ReadableStream`
* You can also use libraries such as' mockjs' to generate data content
* @type string | number | array | object | ReadableStream | buffer
* @type (request: { headers, query, body, params, refererQuery, getCookie }) => any | Promise<any>
*/
body: '',
/**
* If the mock requirement cannot be solved through `body` configuration,
* then it can be achieved by configuring response and exposing the interface of http server
* to realize fully controllable custom configuration in req parameters.
* The parsing of query, body and params has been built-in, so you can use them directly.
* Don't forget to return response data through `res.end()` or skip mock by calling `next()`.
*/
response(req, res, next) {
res.end()
},
/**
* Request validator, return mock data if validated, otherwise do not use current mock.
* This is useful in scenarios where an interface needs to return different data based
* on different input parameters.
* Validators can solve this type of problem well by dividing the same URL into multiple
* mock configurations and determining which one is effective based on the validator.
*
* @type { headers, body, query, params, refererQuery }
* If the validator passed in is an object,
* then the validation method is to deeply compare whether
* `headers/body/query/params/refererQuery` of the requested interface contain
* the `key-value` of the validator.
*
* @type (request) => boolean
* If the validator passed in is a function,
* then the data related to the requested interface will be provided as input parameters
* for users to perform custom validation and return a boolean.
*
*/
validator: {
headers: {},
body: {},
query: {},
params: {},
/**
* refererQuery validates the query parameters in the URL of the request source page,
* which allows for direct modification of parameters in the browser address bar
* to obtain different simulated data.
*/
refererQuery: {}
},
})
// Configure the WebSocket mock
export default defineMock({
/**
* Request address, supports the `/api/user/:id` format.
* The plugin matches the path through `path-to-regexp`.
* @see https://github.com/pillarjs/path-to-regexp
*/
url: '/api/test',
/**
* Value must be explicitly specified as `true`.
* The plugin needs to make a judgment based on this field.
*/
ws: true,
/**
* Configure the WebSocketServer
* @see https://github.com/websockets/ws/blob/master/doc/ws.md#class-websocketserver
* If there are some additional automatically executed tasks or loop
* tasks in the setup function,a callback needs to be passed in
* `onCleanup()` to clear these tasks.
* This is because when the plugin is hot updated,
* it needs to re-execute setup and clear previous tasks; otherwise,
* duplicate tasks may cause conflicts.
* `onCleanup()` can be called multiple times within setup.
* @type `(wss: WebSocketServer, context: SetupContext) => void`
*/
setup(wss, { onCleanup }) {
wss.on('connection', (ws, request) => {
ws.on('message', (rawData) => {})
const timer = setInterval(() => ws.send('data'), 1000)
onCleanup(() => clearInterval(timer))
})
}
})
When defining methods using headers, body, and response, the plugin adds new content to the request and response parameters.
In Request:
The original type of request is Connect.IncomingMessage. The plugin adds data such as query, params, body, refererQuery, and the getCookie(name) method for obtaining cookie information on this basis.
type Request = Connect.IncomingMessage & {
query: object
params: object
body: any
refererQuery: object
getCookie: (name: string, option?: Cookies.GetOption) => string | undefined
}
In Response:
The original type of response is http.ServerResponse<http.IncomingMessage>. The plugin adds setCookie(name, value) method for configuration cookies on this basis.
type Response = http.ServerResponse<http.IncomingMessage> & {
setCookie: (
name: string,
value?: string | null,
option?: Cookies.SetOption,
) => void
}
Tips：
If you write mock files using json/json5, the 'response' method is not supported, as is the function form that uses other fields.
Due to each mock file being compiled as a separate entry point, the local files they depend on are also compiled within. Additionally, each mock file has an independent scope. This means that even if multiple mock files collectively depend on a data.ts file, they cannot share data. If one mock file modifies the data in data.ts, other mock files will not receive the updated data.
To address this, the plugin offers a defineMockData function, which allows using data.ts as a shared data source within mock files.
type defineMockData<T> = (
key: string, // key
initialData: T, // initial data
) => [getter, setter] & { value: T }
data.ts
import { defineMockData } from 'vite-plugin-mock-dev-server'
export default defineMockData('posts', [
{ id: '1', title: 'title1', content: 'content1' },
{ id: '2', title: 'title2', content: 'content2' },
])
*.mock.ts
import { defineMock } from 'vite-plugin-mock-dev-server'
import posts from './data'
export default defineMock([
{
url: '/api/posts',
body: () => posts.value
},
{
url: '/api/posts/delete/:id',
body: (params) => {
const id = params.id
posts.value = posts.value.filter(post => post.id !== id)
return { success: true }
}
}
])
Tips：
The
defineMockDatafunction relies solely on the shared data support provided bymemory. If persistent mock data is required, it is recommended to use anosqldatabase likelowdborlevel.
Custom rules only affect links with dynamic parameters, such as:
/api/user/:id
The priority of the path matching rules built into the plugin can already meet most needs, but if you need more flexible customization of the matching rule priority, you can use the priority parameter.
Exp：
import { defineConfig } from 'vite'
import mockPlugin from 'vite-plugin-mock-dev-server'
export default defineConfig({
plugins: [
mockPlugin({
priority: {
// The priority of matching rules is global.
// The rules declared in this option will take priority over the default rules.
// The higher the position of the rule in the array, the higher the priority.
global: ['/api/:a/b/c', '/api/a/:b/c', '/api/a/b/:c'],
// For some special cases where the priority of certain rules needs to be adjusted,
// this option can be used. For example, when a request matches both Rule A and Rule B,
// and Rule A has a higher priority than Rule B, but it is desired for Rule B to take effect.
special: {
// When both A and B or C match, and B or C is at the top of the sort order,
// insert A into the top position.
// The `when` option is used to further constrain the priority adjustment to
// be effective only for certain requests.
'/api/:a/:b/c': {
rules: ['/api/a/:b/:c', '/api/a/b/:c'],
when: ['/api/a/b/c']
},
// If no `when` is specified, it means that all requests matching the rules need to have their priorities adjusted. It can be abbreviated as `[key]: [...rules]`
'/api/:a/b': ['/api/a/:b'],
}
}
})
]
})
Tip:
priorityalthough it can adjust the priority, most of the time you do not need to do so. For some special requests, you can use static rules instead ofpriority, as static rules always have the highest priority.
mock/**/*.mock.{ts,js,mjs,cjs,json,json5}
See more examples： example
exp: Match /api/test, And returns a response body content with empty data
export default defineMock({
url: '/api/test',
})
exp: Match /api/test , And returns a static content data
export default defineMock({
url: '/api/test',
body: { a: 1 },
})
exp: Only Support GET Method
export default defineMock({
url: '/api/test',
method: 'GET'
})
exp: In the response header, add a custom header and cookie
export default defineMock({
url: '/api/test',
headers: { 'X-Custom': '12345678' },
cookies: { 'my-cookie': '123456789' },
})
export default defineMock({
url: '/api/test',
headers({ query, body, params, headers }) {
return { 'X-Custom': query.custom }
},
cookies() {
return { 'my-cookie': '123456789' }
}
})
exp: Define multiple mock requests for the same URL and match valid rules with validators
export default defineMock([
// Match /api/test?a=1
{
url: '/api/test',
validator: {
query: { a: 1 },
},
body: { message: 'query.a == 1' },
},
// Match /api/test?a=2
{
url: '/api/test',
validator: {
query: { a: 2 },
},
body: { message: 'query.a == 2' },
},
{
// `?a=3` will resolve to `validator.query`
url: '/api/test?a=3',
body: { message: 'query.a == 3' }
},
// Hitting the POST /api/test request, and in the request body,
// field a is an array that contains items with values of 1 and 2.
{
url: '/api/test',
method: ['POST'],
validator: { body: { a: [1, 2] } }
}
])
exp: Response Delay
export default defineMock({
url: '/api/test',
delay: 6000, // delay 6 seconds
})
exp: The interface request failed
export default defineMock({
url: '/api/test',
status: 502,
statusText: 'Bad Gateway'
})
exp: Dynamic route matching
export default defineMock({
url: '/api/user/:userId',
body({ params }) {
return { userId: params.userId }
}
})
The userId in the route will be resolved into the request.params object.
exp:** Use the buffer to respond data
import { Buffer } from 'node:buffer'
// Since the default value of type is json,
// although buffer is used for body during transmission,
// the content-type is still json.
export default defineMock({
url: 'api/buffer',
body: Buffer.from(JSON.stringify({ a: 1 }))
})
// When the type is buffer, the content-type is application/octet-stream.
// The data passed in through body will be converted to a buffer.
export default defineMock({
url: 'api/buffer',
type: 'buffer',
// Convert using Buffer.from(body) for internal use
body: { a: 1 }
})
exp: Response file type
Simulate file download, and pass in the file reading stream.
import { createReadStream } from 'node:fs'
export default defineMock({
url: '/api/download',
// When you are unsure of the type, you can pass in the file name for internal parsing by the plugin.
type: 'my-app.dmg',
body: () => createReadStream('./my-app.dmg')
})
<a href="/api/download" download="my-app.dmg">Download File</a>
exp: Use mockjs:
import Mock from 'mockjs'
export default defineMock({
url: '/api/test',
body: Mock.mock({
'list|1-10': [{
'id|+1': 1
}]
})
})
You need install mockjs
exp: Use response to customize the response
export default defineMock({
url: '/api/test',
response(req, res, next) {
const { query, body, params, headers } = req
console.log(query, body, params, headers)
res.status = 200
res.setHeader('Content-Type', 'application/json')
res.end(JSON.stringify({
query,
body,
params,
}))
}
})
exp: Use json / json5
{
"url": "/api/test",
"body": {
"a": 1
}
}
exp: multipart, upload files.
use formidable to support.
<form action="/api/upload" method="post" enctype="multipart/form-data">
<p>
<span>file: </span>
<input type="file" name="files" multiple="multiple">
</p>
<p>
<span>name:</span>
<input type="text" name="name" value="mark">
</p>
<p>
<input type="submit" value="submit">
</p>
</form>
fields files mapping to formidable.File
export default defineMock({
url: '/api/upload',
method: 'POST',
body(req) {
const body = req.body
return {
name: body.name,
files: body.files.map((file: any) => file.originalFilename),
}
},
})
exp: Graphql
import { buildSchema, graphql } from 'graphql'
const schema = buildSchema(`
type Query {
hello: String
}
`)
const rootValue = { hello: () => 'Hello world!' }
export default defineMock({
url: '/api/graphql',
method: 'POST',
body: async (request) => {
const source = request.body.source
const { data } = await graphql({ schema, rootValue, source })
return data
},
})
fetch('/api/graphql', {
method: 'POST',
body: JSON.stringify({ source: '{ hello }' })
})
exp: WebSocket Mock
// ws.mock.ts
export default defineMock({
url: '/socket.io',
ws: true,
setup(wss, { onCleanup }) {
const wsMap = new Map()
wss.on('connection', (ws, req) => {
const token = req.getCookie('token')
wsMap.set(token, ws)
ws.on('message', (raw) => {
const data = JSON.parse(String(raw))
if (data.type === 'ping')
return
// Broadcast
for (const [_token, _ws] of wsMap.entires()) {
if (_token !== token)
_ws.send(raw)
}
})
})
wss.on('error', (err) => {
console.error(err)
})
onCleanup(() => wsMap.clear())
}
})
// app.ts
const ws = new WebSocket('ws://localhost:5173/socket.io')
ws.addEventListener('open', () => {
setInterval(() => {
// heartbeat
ws.send(JSON.stringify({ type: 'ping' }))
}, 1000)
}, { once: true })
ws.addEventListener('message', (raw) => {
console.log(raw)
})
In some scenarios, it may be necessary to use the data provided by mock services for display purposes, but the project may have already been packaged, built and deployed without support from Vite and this plugin's mock service. Since this plugin supports importing various node modules in mock files at the design stage, the mock file cannot be inline into client build code.
To meet such scenarios, on one hand, the plugin provides support under vite preview, and on the other hand, it also builds a small independent mock service application that can be deployed to relevant environments during vite build. This can then be forwarded through other HTTP servers like Nginx to actual ports for mock support.
The default output is built into the directory dist/mockServer, generating files as follows:
./mockServer
├── index.js
├── mock-data.js
└── package.json
In this directory, execute npm install to install dependencies, and then execute npm start to start the mock server.
The default port is 8080.
You can access related mock interfaces through localhost:8080/.
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FAQs
Vite Plugin for API mock dev server.
The npm package vite-plugin-mock-dev-server receives a total of 1,457 weekly downloads. As such, vite-plugin-mock-dev-server popularity was classified as popular.
We found that vite-plugin-mock-dev-server demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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