[Home](./index.md) > [rc-js-util](./rc-js-util.md) > [ReferenceCounter](./rc-js-util.referencecounter.md) > [(constructor)](./rc-js-util.referencecounter._constructor_.md) ## ReferenceCounter.(constructor) Constructs a new instance of the `ReferenceCounter` class **Signature:** ```typescript constructor(onZeroReference?: (key: TKey) => void); ``` ## Parameters

Parameter	Type	Description
onZeroReference	(key: TKey) => void	_(Optional)_