Test IndexedDB's behavior put()ing with null key On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". indexedDB = self.indexedDB || self.webkitIndexedDB || self.mozIndexedDB || self.msIndexedDB || self.OIndexedDB; indexedDB.deleteDatabase(dbname) indexedDB.open(dbname) objectStore = db.createObjectStore('bar'); Expecting exception from objectStore.put({}, null); PASS Exception was thrown. PASS code is 0 PASS ename is 'DataError' Exception message: Failed to store record in an IDBObjectStore: The parameter is not a valid key. PASS successfullyParsed is true TEST COMPLETE