In most cases, you’re already using it. You don’t have to download, configure, and maintain Sencha Cmd. You really have no direct interaction with it, either with Ext JS + Reactor or ExtReact. The Webpack plugin has an npm-wrapped version of Sencha Cmd as a dependency, so it handles all of that for you. It calls your code, looks for the components you’re using, and feeds all of that information into Sencha Cmd. Then, Cmd can build a minimal bundle. It’s all handled automatically.
