Offline Application Cache Debugging

offline_debug.js

// Adapted from a snippet by Jonathan Stark

var cacheStatusValues = [];
cacheStatusValues[0] = 'uncached';
cacheStatusValues[1] = 'idle';
cacheStatusValues[2] = 'checking';
cacheStatusValues[3] = 'downloading';
cacheStatusValues[4] = 'updateready';
cacheStatusValues[5] = 'obsolete';

var cache = window.applicationCache;
cache.addEventListener('cached', logEvent, false);
cache.addEventListener('checking', logEvent, false);
cache.addEventListener('downloading', logEvent, false);
cache.addEventListener('error', logEvent, false);
cache.addEventListener('noupdate', logEvent, false);
cache.addEventListener('obsolete', logEvent, false);
cache.addEventListener('progress', logEvent, false);
cache.addEventListener('updateready', logEvent, false);

function logEvent(e) {
  var online, status, type, message;
  // This check might be confusing on Chrome, where
  // navigator.onLine tends to always evaluate true
  online = (navigator.onLine) ? 'yes' : 'no';
  status = cacheStatusValues[cache.status];
  type = e.type;
  message = 'online: ' + online;
  message+= ', event: ' + type;
  message+= ', status: ' + status;
  if (type == 'error' && navigator.onLine) {
    message+= ' (check manifest syntax)';
  }
  console.log(message);
}

window.applicationCache.addEventListener('updateready', function() {
  window.applicationCache.swapCache();
  console.log('swap cache has been called');
}, false);

setInterval(function() {
 cache.update();
}, 10000);