getOpenItems of ui.tree, Methods Webix Docs
returns ids of the opened branches
array getOpenItems();
Example
tree = webix.ui({
view:"tree",
...
})
tree.getOpenItems();
Details
For example, for the tree as in:

data: [
{id:"root", value:"Cars", open:true, data:[
{ id:"1", open:true, value:"Toyota", data:[
{ id:"1.1", value:"Avalon" },
{ id:"1.2", value:"Corolla" },
{ id:"1.3", value:"Camry" }
]},
{ id:"2", value:"Skoda", open:true, data:[
{ id:"2.1", value:"Octavia" },
{ id:"2.2", value:"Superb" }
]}
]}
]
the method returns the following array:
["1", "2", "root"]
See also