Tooltips are a simple mechanism to give the user more information about chart items. There are two basic ways of populating tooltips: pre-loading and dynamic loading.

Preloading loads the data onto the d property for all nodes up front, which is why it's mostly convenient only for relatively small datasets. Preloading is used in this demo.

Dynamic loading brings the data in dynamically when each node is hovered, which makes it suitable even for very large datasets.

Object format used:

• node 'd' property

Key function used:

• Chart Events
  • 'drag-move'
  • 'hover'