columns.expandable Boolean (default: false)

If set to true, the column will show the icons that are used for expanding and collapsing child rows. By default, the first column of the TreeList is expandable.

An expandable column cannot hold commands.

Example - making the second column expandable

<div id="treeList"></div>
<script>
    $("#treeList").kendoTreeList({
        columns: [
            { field: "name" },
            { field: "age", expandable: true }
        ],
        dataSource: {
            data: [
                { id: 1, parentId: null, name: "Jane Doe", age: 22 },
                { id: 2, parentId: 1, name: "John Doe", age: 24 }
            ]
        }
    });
</script>