cache-offline.js revision 51cd1e3c989b1d9414c7749c72c369f0325cdb8e
/**
* Extends Cache utility with offline functionality.
* @class CacheOffline
* @extends Cache
* @constructor
*/
function CacheOffline() {
CacheOffline.superclass.constructor.apply(this, arguments);
}
var localStorage = Y.config.win.localStorage,
isDate = Y.Lang.isDate,
JSON = Y.JSON,
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline static properties
//
/////////////////////////////////////////////////////////////////////////////
cacheOfflineStatic = {
/**
* Class name.
*
* @property NAME
* @type String
* @static
* @final
* @value "cacheOffline"
*/
NAME: "cacheOffline",
ATTRS: {
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline Attributes
//
/////////////////////////////////////////////////////////////////////////////
/**
* @attribute sandbox
* @description A string that must be passed in via the constructor.
* This identifier is used to sandbox one cache instance's entries
* from another. Calling the cache instance's flush and length methods
* or get("entries") will apply to only these sandboxed entries.
* @type String
* @default "default"
* @initOnly
*/
sandbox: {
value: "default",
initOnly: true
},
/**
* @attribute expires
* @description Absolute Date when data expires or
* relative number of milliseconds. Zero disables expiration.
* @type Date | Number
* @default 0
*/
expires: {
value: 86400000, //one day
validator: function(v) {
return Y.Lang.isDate(v) || (Y.Lang.isNumber(v) && v >= 0);
}
},
/**
* @attribute max
* @description Disabled.
* @readOnly
* @default null
*/
max: {
value: null,
readOnly: true
},
/**
* @attribute uniqueKeys
* @description Always true for CacheOffline.
* @readOnly
* @default true
*/
uniqueKeys: {
value: true,
readOnly: true,
setter: function() {
return true;
}
}
},
/**
* Removes all items from all sandboxes. Useful if localStorage has
* exceeded quota. Only supported on browsers that implement HTML 5
* localStorage.
*
* @method flushAll
* @static
*/
flushAll: function() {
var store = localStorage, key;
if(store) {
if(store.clear) {
store.clear();
}
// FF2.x and FF3.0.x
else {
for (key in store) {
if (store.hasOwnProperty(key)) {
store.removeItem(key);
delete store[key];
}
}
}
Y.log("All sandboxes of OfflineCache flushed", "info", "cache");
}
else {
Y.log("Could not flush all OfflineCache sandboxes.", "warn", "cache");
}
}
},
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline events
//
/////////////////////////////////////////////////////////////////////////////
/**
* @event error
* @description Fired when an entry could not be added, most likely due to
* exceeded browser quota.
* <dl>
* <dt>error (Object)</dt> <dd>The error object.</dd>
* </dl>
*/
cacheOfflinePrototype = localStorage ? {
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline protected methods
//
/////////////////////////////////////////////////////////////////////////////
/**
* Always return null.
*
* @method _setMax
* @protected
*/
_setMax: function(value) {
return null;
},
/**
* Gets size.
*
* @method _getSize
* @protected
*/
_getSize: function() {
var count = 0,
i=0,
l=localStorage.length;
for(; i<l; ++i) {
// Match sandbox id
if(localStorage.key(i).indexOf(this.get("sandbox")) === 0) {
count++;
}
}
return count;
},
/**
* Gets all entries.
*
* @method _getEntries
* @protected
*/
_getEntries: function() {
var entries = [],
i=0,
l=localStorage.length,
sandbox = this.get("sandbox");
for(; i<l; ++i) {
// Match sandbox id
if(localStorage.key(i).indexOf(sandbox) === 0) {
entries[i] = JSON.parse(localStorage.key(i).substring(sandbox.length));
}
}
return entries;
},
/**
* Adds entry to cache.
*
* @method _defAddFn
* @param e {Event.Facade} Event Facade with the following properties:
* <dl>
* <dt>entry (Object)</dt> <dd>The cached entry.</dd>
* </dl>
* @protected
*/
_defAddFn: function(e) {
var entry = e.entry,
request = entry.request,
expires = this.get("expires");
entry.expires = isDate(expires) ? expires :
(expires ? new Date(new Date().getTime() + this.get("expires")) : null);
try {
localStorage.setItem(this.get("sandbox")+JSON.stringify({"request":request}), JSON.stringify(entry));
Y.log("Cached offline entry: " + Y.dump(entry), "info", "cache");
}
catch(error) {
this.fire("error", {error:error});
Y.log("Could not cache offline entry: " + Y.dump(entry) +
" due to error: " + Y.dump(error), "warn", "cache");
}
},
/**
* Flushes cache.
*
* @method _defFlushFn
* @param e {Event.Facade} Event Facade object.
* @protected
*/
_defFlushFn: function(e) {
var key,
i=localStorage.length-1;
for(; i>-1; --i) {
// Match sandbox id
key = localStorage.key(i);
if(key.indexOf(this.get("sandbox")) === 0) {
localStorage.removeItem(key);
}
}
},
/////////////////////////////////////////////////////////////////////////////
//
// CacheOffline public methods
//
/////////////////////////////////////////////////////////////////////////////
/**
* Adds a new entry to the cache of the format
* {request:request, response:response, expires: expires}.
*
* @method add
* @param request {Object} Request value must be a String or JSON.
* @param response {Object} Response value must be a String or JSON.
*/
/**
* Retrieves cached object for given request, if available.
* Returns null if there is no cache match.
*
* @method retrieve
* @param request {Object} Request object.
* @return {Object} Cached object with the properties request, response,
* and expires, or null.
*/
retrieve: function(request) {
this.fire("request", {request: request});
var entry, expires, cached;
try {
request = this.get("sandbox")+JSON.stringify({"request":request});
try {
entry = JSON.parse(localStorage.getItem(request));
}
catch(e) {
}
}
catch(e2) {
}
if(entry) {
entry.cached = new Date(entry.cached);
expires = entry.expires;
expires = !expires ? null : new Date(expires);
if(!expires || new Date() < expires) {
entry.expires = expires;
this.fire("retrieve", {entry: entry});
Y.log("Retrieved offlinecached response: " + Y.dump(entry) +
" for request: " + Y.dump(request), "info", "cache");
return entry;
}
}
return null;
}
} : {
/**
* Always return null.
*
* @method _setMax
* @protected
*/
_setMax: function(value) {
return null;
},
/**
* Adds entry to cache with an expires property.
*
* @method _defAddFn
* @param e {Event.Facade} Event Facade with the following properties:
* <dl>
* <dt>entry (Object)</dt> <dd>The cached entry.</dd>
* </dl>
* @protected
*/
_defAddFn: function(e) {
var expires = this.get("expires");
e.entry.expires = isDate(expires) ? expires :
(expires ? new Date(new Date().getTime() + this.get("expires")) : null);
Y.log("Added expires property: " + Y.dump(e.entry), "info", "cache");
CacheOffline.superclass._defAddFn.call(this, e);
},
/**
* Overrides the default method to check for expired entry.
* Returns true if current request matches the cached request, otherwise
* false. Implementers should override this method to customize the
* cache-matching algorithm.
*
* @method _isMatch
* @param request {Object} Request object.
* @param entry {Object} Cached entry.
* @return {Boolean} True if current request matches given cached request
* and entry has not expired, false otherwise.
* @protected
*/
_isMatch: function(request, entry) {
if(!entry.expires || new Date() < entry.expires) {
return (request === entry.request);
}
return false;
}
};
Y.mix(CacheOffline, cacheOfflineStatic);
Y.extend(CacheOffline, Y.Cache, cacheOfflinePrototype);
Y.CacheOffline = CacheOffline;