The correctly implemented ViewModel hierarchy in Ext 5.x MVVM applications provides for more robust, modularized and well-written large applications. Read this article to write big, yet maintainable, expandable and bugless applications.
Chained Stores, introduced in ExtJS 5, allow to use one store in multiple views with independent filtering and sorting. This article discusses what they really are, what are drawbacks and it also provides a playground application that.
ExtJS grid renderers are the powerful tool that can, if used correctly, greatly enhance the user interface. However, you can run into several gotchas. This article demonstrates what problems can renderers introduce and explains how to avoid them.