API Reference > imodeljs-frontend > QuantityFormatting > QuantityFormatter > onActiveFormattingUnitSystemChanged onActiveFormattingUnitSystemChanged Readonly onActiveFormattingUnitSystemChanged: BeUiEvent<FormattingUnitSystemChangedArgs> = ... Called after the active unit system is changed. The system will report the UnitSystemKey/name of the the system that was activated. Defined in core/frontend/src/quantity-formatting/QuantityFormatter.ts Line 331 Last Updated: 11 June, 2024