ExtJS：向TreePanel中的节点添加单击操作

[revised] I'm creating a TreePanel in ExtJs that is loading its children from a JSON file. I'm having trouble adding a click action to the nodes. I'm not sure whether it's added in the script creating the tree, or if its added as a property in the JSON, and if so, what the syntax would be. Any help would be appreciated! Please provide an example if possible.[revised] I'm creating a TreePanel in ExtJs tha