Get all of the nodes in zTree
Please use zTree object to executing the method.
return all of the nodes
1. This array is a collection of the root nodes (the default child nodes are in the 'children' attributes);
2. Traverse all the nodes need to use recursion, or the use of transformToArray() method make the nodes to be a simple array.
3. For the asynchronous loading mode, can't get the nodes which are yet loaded.
var treeObj = $.fn.zTree.getZTreeObj("tree");
var nodes = treeObj.getNodes();