Method getIndex does not exists

[projct1]

trafficstars

https://skr.sh/sAMuWUw7pSj

onDrop: function(event, treeId, treeNodes, targetNode, moveType) {
    console.log(treeNodes[0].getIndex());
});

Got error Uncaught TypeError: treeNodes[0].getIndex is not a function

[zTree]

please check the version of your zTree js file.