Esri plans to implement group layers for ArcGIS Online feature services in the future, but until then, here is an alternate method to clean-up content in a web app by configuring Group Layer Lists to organize layers in Web AppBuilder.
Building a Hoops Tracker App with ArcGIS Solutions is a Three-Point Play
Hoops Tracker is a Esri Story Map that displays information for the 2018 Class 1A and 2A Boys Basketball Tournaments in separate web mapping applications, paired with a view of IHSA's interactive ScoreZone web page and other IHSA links.
Extend your Apps with Custom Widgets in Web AppBuilder
Cloudpoint has successfully upgraded a number of Flex mapping applications to Javascript applications in the past year using Web AppBuilder (WAB). Some of the components that make these apps stand out are widgets that improve the user experience with the app. . Esri packages a number of basic widgets in WAB, but some developers have designed custom widgets that extend the functionality of these applications. A number of these custom widgets were available in the Flex apps and we wanted to honor our client's wishes to provide the same tools and functionality. Here we highlight a few of the custom widgets we configured for our clients.