Example of using mswjs interceptors

intercept.js

import { BatchInterceptor } from '@mswjs/interceptors'
import { ClientRequestInterceptor } from '@mswjs/interceptors/ClientRequest'
import { FetchInterceptor } from '@mswjs/interceptors/fetch'
import http from 'http'

const interceptor = new BatchInterceptor({
  name: 'my-interceptor',
  interceptors: [new ClientRequestInterceptor(), new FetchInterceptor()],
})

// Enable the interception of requests.
interceptor.apply()

// Listen to any "http.ClientRequest" being dispatched,
// and log its method and full URL.
interceptor.on('request', ({ request, requestId }) => {
  console.log('⚡️' + request.method, request.url)
})

interceptor.on('request', ({ request, requestId }) => {
  request.respondWith(
    new Response(
      JSON.stringify({
        firstName: 'John',
        lastName: 'Maverick',
      }),
      {
        status: 201,
        statusText: 'Created',
        headers: {
          'Content-Type': 'application/json',
        },
      }
    )
  )
})

// Listen to any responses sent to "http.ClientRequest".
// Note that this listener is read-only and cannot affect responses.
interceptor.on('response', async ({ response, isMockedResponse, request, requestId }) => {
  console.log('response to %s %s was:', request.method, request.url, response.status)

  const respText = await response.clone().text()
  console.log('response', respText)

  const reqText = await request.clone().text()
  console.log('request', reqText)
})

const server = http.createServer((req, res) => {
  res.statusCode = 200
  res.setHeader('Content-Type', 'application/json')
  res.end(JSON.stringify({ method: req.method, headers: req.headers }))
})

server.listen(3000, '127.0.0.1', () => {
  console.log('Server running at http://127.0.0.1:3000/')
})

const data = JSON.stringify({
  todo: 'Buy the milk',
})

const response = await fetch('http://localhost:3000/', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: data,
})

const result = await response.json()
console.log('Result:', result)

interceptor.dispose()
server.close()