Event that is emitted on a particular UI component before it is fist rendered, only once. Instances should not be reused.
UIBeforeRenderEventis emitted only once, before a component is rendered the first time, and can be observed using an
onBeforeRenderpreset handler property. By contrast, a plain
UIComponentEventis emitted each time after a UI component is rendered, i.e. whenever a change occurs to its display properties (or its child components’), which can be observed using an
onRenderedpreset handler property.
<TSource extends UIComponent>(source: TSource): UIBeforeRenderEvent<TSource>
Event source UI component.