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[Home](./index.md) &gt; [@empathyco/x-components](./x-components.md) &gt; [StateSelector](./x-components.stateselector.md) &gt; [filter](./x-components.stateselector.filter.md)

## StateSelector.filter() method

Asserts if the event should really be emitted taking into account the new and old values and the module state.

**Signature:**

```typescript
filter?(newValue: ReturnType, oldValue: ReturnType, state: State): boolean;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  newValue | ReturnType | The new value. |
|  oldValue | ReturnType | The old value. |
|  state | State | The state of the [XModule](./x-components.xmodule.md) where this selector is used. |

**Returns:**

boolean

True if the value has really changed.

## Remarks

This function exist because Vue will not stop reactivity propagation if the observed variable is an `object`<!-- -->, an `Array`<!-- -->, or the `deep` mode has been enabled.