How to listen the node Expand/Collapse state in FlexyGantt?

Sometimes, user might want to listen the NodeExpansionStateChanged event, which is raised when the node Expand/Collapse changed state in FlexyGantt. The below code will explain how to do this.

$(document).ready(function (){

................

var flexyGantt = $gantt_container.data("FlexyGantt");

flexyGantt.FlatItemsSource.NodeExpansionStateChanged.subscribe(function (hierData) {

var isExpanded = hierData.IsExpanded();

});