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.
If a value is successfully found, then a structured clone of it is created and set as the result of the request object: this returns the record the key is associated with.
There is a performance cost associated with looking at the value property of a cursor, because the object is created lazily. To use a feature like getAll(), Gecko would have to create all the objects at once. If you were just interested in looking at each of the keys, for instance, it would be much more efficient to use a cursor. If you were trying to get an array of all the objects in an object store, though, you could use getAll().
If a key is successfully found it is set as the result of the request object: this returns the primary key of the record the key is associated with, not the whole record as IDBIndex.get does.
The isAutoLocale read-only property of the IDBIndex interface returns a Boolean indicating whether the index had a locale value of auto specified upon its creation (see createIndex()'s optionalParameters.)
The locale read-only property of the IDBIndex interface returns the locale of the index (for example en-US, or pl) if it had a locale value specified upon its creation (see createIndex()'s optionalParameters.) Note that this property always returns the current locale being used in this index, in other words, it never returns "auto".