Response patching

You can combine original and mocked responses using a technique called response patching. It involves performing the intercepted request as-is, getting its original response, and modifying it as you want.

Use the bypass() function from msw to perform any Fetch API Request, bypassing any otherwise matching request handlers and also preventing an infinite loop caused by the handler where you’re using bypass():

import { http, HttpResponse, bypass } from 'msw'
 
http.get('/resource', async ({ request }) => {
  // Get the original JSON response from the server.
  const originalData = await bypass(request).then((response) => response.json())
 
  return HttpResponse.json({
    // Combine the original data with the mocked data.
    ...originalData,
    id: 'mocked-id',
  })
})