使用AJAX获取数据

const fetchPermissionsEpic = (
  action$,
  state$,
  { ajax },
) => (
  action$
  .pipe(
    ofType(FETCH_PERMISSIONS),
    map(state$.value)
    map(accessTokenSelector),
    switchMap(accessToken => (
      ajax({
        crossDomain: true,
        headers: {
          'Authorization': `Bearer ${accessToken}`,
        },
        url: 'https://example.com/permissions',
      })
      .pipe(
        pluck('response'),
        map(storePermissions),
      )
    )),
  )
)