jsTree is jquery plugin, that provides interactive trees. jsTree is easily extendable, themable and configurable. One of noticeable feature is its tri-state checkbox. States are checked, unchecked and indeterminate.
Indeterminate state is when not all child items are checked then the check state of the parent becomes indeterminate.
Like below, the state of "Root node 2" is Indeterminate as not all child nodes are checked.