Excluding certain files from being cached for online-offline detection

[lynxionxs]

I want to reliably check if the pwa is online or offline. Using a small file on the production server for that. But how can i exclude only that file from being cached by the PWA?

// Example
pwa: {
  workbox: {
    enabled:true,
    exclude: [
      /ping\.txt$/,
    ]
  }
}