`HasValueListener`

The HasValueListener type describes a function that is used to listen to a Value being added to or removed from the Store.

(
  store: Store,
  valueId: Id,
  hasValue: boolean,
): void

	Type	Description
`store`	`Store`	A reference to the `Store` that changed.
`valueId`	`Id`	The `Id` of the `Value` that changed.
`hasValue`	`boolean`	Whether the `Value` now exists or not.
returns	`void`	This has no return value.

A HasValueListener is provided when using the addHasValueListener method. See that method for specific examples.

When called, a HasValueListener is given a reference to the Store and the Id of Value that changed. It is also given a flag to indicate whether the Value now exists (having not done previously), or does not (having done so previously).

Since

v4.4.0