Template.flexboxLayout.events({ 'transitionend .sidebarMenu'(event) { if (!event.target.classList.contains('sidebarMenu')) { return; } window.ResizeViewportManager.handleResize(); } }); Template.flexboxLayout.helpers({ leftSidebarOpen() { return Template.instance().data.state.get('leftSidebar'); }, rightSidebarOpen() { return Template.instance().data.state.get('rightSidebar'); } });