In IndexedDB, key paths are used to specify which property within an object should be used as the key when storing data in an object store. There are different types of key paths that can be used:

String Key Path : This is the most common type of key path. It specifies the name of a property within the stored object that should be used as the key. For example:

var objectStore = db.createObjectStore("storeName", { keyPath: "id" });?

In this example, the property named "id" within the stored objects will be used as the key.


Array Key Path : An array key path allows specifying a compound key composed of multiple properties. The values of these properties, when combined, form a composite key. For example:

var objectStore = db.createObjectStore("storeName", { keyPath: ["lastName", "firstName"] });?

In this example, the compound key is composed of the "lastName" and "firstName" properties of the stored objects.
Implicit Key Path : If no key path is specified, IndexedDB automatically generates keys for objects stored in the object store. These keys are numeric and monotonically increasing. This is useful when the data does not have a natural key or when the key is not explicitly specified. For example:

var objectStore = db.createObjectStore("storeName", { autoIncrement: true });?

In this case, the keys for stored objects will be automatically generated.

Each of these key path types has its use cases and considerations. Developers should choose the appropriate key path type based on the requirements of their application and the structure of the data being stored in IndexedDB.