# PositioningFunction

typedef

[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/dom/position.ts#L527)

#### Parameters

* `elementRect: Rect`

  The rect of the element to be positioned.

* `targetRect: Rect`

  The rect of the target the element (its rect) is relatively positioned to.

* `viewportRect: Rect`

  The rect of the visual browser viewport.

* `limiterRect?: Rect`

#### Returns

* `DomPositioningFunctionResult | null`

  When the function returns `null`, it will not be considered by [`getOptimalPosition`](module_utils_dom_position.md#function-getOptimalPosition).

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Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)