Offline storage, html5 offline storage

Offline storage, html5 offline storage

I. Support Detection

If (window. applicationCache) {// the browser supports offline storage} else {// the browser does not support offline storage} support: IE9 and earlier versions do not support

2. manifest File

• Introduce the manifest file:

• Manifest file format (Note ):

• Cache manifest # The first line must be the cache manifestCACHE: # All the items to be cached must be placed in the CACHE: css/B .css # Always put requests from the NETWORK on the NETWORK: css/a.css FALLBACK # redirect css/c.css/a.css after access failure

  • CACHE: CACHE all specified files locally.
  • NETWORK: the specified file always requests the latest from the NETWORK.
  • FALLBACK: if the specified file cannot be found, it will be redirected to the new address.

Iii. Status

• ApplicationCache. status
• 0 === not cached
• 1 === idle (the cache is in the latest status)
• 2 === checking
• 3 === downloading
• 4 === Update ready
• 5 === cache expiration

4. update: actively update the cache

// Update setInterval (function () {applicationCache. update () ;}, 5000) every 5 seconds );

5. Event updateready: when a new cache is available and the update is complete, the event progress event is triggered: when a new cache is in the process of downloading, this event will be continuously triggered.

• The event objects in progress include loaded and total. Loaded indicates the files already loaded. total indicates the total number of files to be updated.

Other events:

• Checking event: checking
• Downloading event: downloading
• Updatereadey event: update complete
• Obsolete event: cache expiration
• Cached event: idle, the cache is in the latest status
• Error Event: error
• Noupdate event: Check that the update is complete and no update is required.