function getCacheService() { var nsCacheService = Components.classes["@mozilla.org/network/cache-service;1"]; var service = nsCacheService.getService(Components.interfaces.nsICacheService); return service; } function createCacheSession(clientID, storagePolicy, streamable) { var service = getCacheService(); var nsICache = Components.interfaces.nsICache; var session = service.createSession(clientID, storagePolicy, streamable); return session; } function openCacheEntry(clientID, url) { var nsICache = Components.interfaces.nsICache; var session = createCacheSession(clientID, nsICache.STORE_ANYWHERE, false); var entry = session.openCacheEntry(url, nsICache.ACCESS_READ_WRITE); return entry; } function wrapString(str) { var nsISupportsCString = Components.interfaces.nsISupportsCString; var factory = Components.classes["@mozilla.org/supports-cstring;1"]; var wrapper = factory.createInstance(nsISupportsCString); wrapper.data = str; return wrapper; } function test() { var data = wrapString("javascript"); var entry = openCacheEntry("javascript", "theme:button"); entry.cacheElement = data; entry.markValid(); entry.close(); var newEntry = openCacheEntry("javascript", "theme:button"); if (newEntry.cacheElement === data) print("object cache works."); else print("object cache failed."); } test();