Lazy loading is useful when you are dealing with large hierarchical data sources and would like to avoid the delays involved in loading the entire data set at once.
The TreeView control makes lazy-loading super easy. Only two steps are required:
The tree in example below starts with three lazy-loaded nodes. When you expand them, the lazyLoadFunction is invoked. The function uses a timeout to simulate an http delay and returns data for three child nodes, one of which is also a lazy-loaded node.