Function getResponse

test/mockServiceWorker.js:187–269

(event, client, requestId)

}

async function getResponse(event, client, requestId) {
  const { request } = event

  // Clone the request because it might've been already used
  // (i.e. its body has been read and sent to the client).
  const requestClone = request.clone()

  function passthrough() {
    // Cast the request headers to a new Headers instance
    // so the headers can be manipulated with.
    const headers = new Headers(requestClone.headers)

    // Remove the "accept" header value that marked this request as passthrough.
    // This prevents request alteration and also keeps it compliant with the
    // user-defined CORS policies.
    const acceptHeader = headers.get('accept')
    if (acceptHeader) {
      const values = acceptHeader.split(',').map((value) => value.trim())
      const filteredValues = values.filter(
        (value) => value !== 'msw/passthrough',
      )

      if (filteredValues.length > 0) {
        headers.set('accept', filteredValues.join(', '))
      } else {
        headers.delete('accept')
      }
    }

    return fetch(requestClone, { headers })
  }

  // Bypass mocking when the client is not active.
  if (!client) {
    return passthrough()
  }

  // Bypass initial page load requests (i.e. static assets).
  // The absence of the immediate/parent client in the map of the active clients
  // means that MSW hasn't dispatched the "MOCK_ACTIVATE" event yet
  // and is not ready to handle requests.
  if (!activeClientIds.has(client.id)) {
    return passthrough()
  }

  // Notify the client that a request has been intercepted.
  const requestBuffer = await request.arrayBuffer()
  const clientMessage = await sendToClient(
    client,
    {
      type: 'REQUEST',
      payload: {
        id: requestId,
        url: request.url,
        mode: request.mode,
        method: request.method,
        headers: Object.fromEntries(request.headers.entries()),
        cache: request.cache,