| cached | Fired after the first cache of the manifest. |
| checking | Checking for an update. Always the first event fired in the sequence. |
| downloading | An update was found. The browser is fetching resources. |
| error | The manifest returns 404 or 410, the download failed or the manifest changed while the download was in progress. |
| noupdate | Fired after the first download of the manifest. |
| obsolete | Fired if the manifest file returns a 404 or 410. |
| progress | Fired for each resource listed in the manifest as it is being fetched. |
| updateready | Fired when the manifest resources have been newly redownloaded. |