In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. For a full working example, see our To-do Notifications app (view example live.)
IDBIndex interface of the IndexedDB API provides asynchronous access to an index in a database. An index is a kind of object store for looking up records in another object store, called the referenced object store. You use this interface to retrieve data.
A key range can be a single value or a range with upper and lower bounds or endpoints. If the key range has both upper and lower bounds, then it is bounded; if it has no bounds, it is unbounded. A bounded key range can either be open (the endpoints are excluded) or closed (the endpoints are included). To retrieve all keys within a certain range, you can use the following code constructs:
The IDBLocaleAwareKeyRange interface of the IndexedDB API is a Firefox-specific version of IDBKeyRange — it functions in exactly the same fashion, and has the same properties and methods, but it is intended for use with IDBIndex objects when the original index had a locale value specified upon its creation (see createIndex()'s optionalParameters) — that is, it has locale aware sorting enabled.
The request object does not initially contain any information about the result of the operation, but once information becomes available, an event is fired on the request, and the information becomes available through the properties of the IDBRequest instance.
Note that as of Firefox 40, IndexedDB transactions have relaxed durability guarantees to increase performance (see bug 1112702.) Previously in a readwrite transaction IDBTransaction.oncomplete was fired only when all data was guaranteed to have been flushed to disk. In Firefox 40+ the complete event is fired after the OS has been told to write the data but potentially before that data has actually been flushed to disk. The complete event may thus be delivered quicker than before, however, there exists a small chance that the entire transaction will be lost if the OS crashes or there is a loss of system power before the data is flushed to disk. Since such catastrophic events are rare most consumers should not need to concern themselves further.
The IDBVersionChangeEvent interface of the IndexedDB API indicates that the version of the database has changed, as the result of an IDBOpenDBRequest.onupgradeneeded event handler function.
The IIRFilterNode interface of the Web Audio API is a AudioNode processor which implements a general infinite impulse response (IIR) filter; this type of filter can be used to implement tone control devices and graphic equalizers as well. It lets the parameters of the filter response be specified, so that it can be tuned as needed.
The parameter passed into the oninstall handler, the InstallEvent interface represents an install action that is dispatched on the ServiceWorkerGlobalScope of a ServiceWorker. As a child of ExtendableEvent, it ensures that functional events such as FetchEvent are not dispatched during installation.