how do I collpase and expand all tree nodes in a Kendo UI treeView based on a button click?

Question

This is not working:

<script type="text/javascript">
            $('#btnCollapseAll').click(function()
            {
                $('#treeview').collapseAll();
            });
</script>

Answer 1

You can use this code

1: collapse

collapse kendoTreeView document

    $("#treeview").kendoTreeView();
            var treeview = $("#treeview").data("kendoTreeView");
            treeview.collapse(document.getElementById("firstItem"));
            $('#btn').click(function () {
                // collapse the node with id="firstItem"

                // collapse all nodes
                treeview.collapse(".k-item");
            });

2:expand

expand kendoTreeView document

 $("#treeview").kendoTreeView();
        var treeview = $("#treeview").data("kendoTreeView");
        treeview.collapse(document.getElementById("firstItem"));
        $('#btn').click(function () {
            // expand the node with id="firstItem"

            // expand all nodes
            treeview.expand(".k-item");
        });

Answer 2

only need to set one property "expanded: false"

    $("#TreeList").kendoTreeList({
    height: 400,
    filterable: false,
    sortable: true,
    columns: [
      { field: "Name", title: "  ", width: 235 },
      { field: "Outstanding", title: "Outstanding", width: 235, template: $("#outstanding-olor-div-template").html() }
    ],
    dataSource: {
        transport: {
            read: {
                url: ServiceUrl ,
                dataType: "json"
            }
        },
        schema: {
            model: {
                id: "Id",
                parentId: "ParentId",
                fields: {
                    ParentId: { field: "ParentId", nullable: true },
                    Id: { field: "Id", type: "number" },
                    Name: { field: "Name" }
                },
                expanded: false
            }
        }
    }
});

Answer 3

        <script>
            $(document).ready(function() {
                $("#treeview").kendoTreeView();
                var treeview = $("#treeview").data("kendoTreeView");

                $("#expandAllNodes").click(function() {
                    treeview.expand(".k-item");
                });

                $("#collapseAllNodes").click(function() {
                    treeview.collapse(".k-item");
                });
            });
        </script>

Answer 4

None of the above answers worked for me because my tree had a lot of data and was set to loadOnDemand: true. I included my solution below that recursively expands each node as it is loaded in the tree.

The use case for me was that I wanted to expand all nodes when filtering the tree, but leave them collapsed when browsing the full tree (thus the settings needed to stay loadOnDemad: true)

Here it is:

        // Expands entire tree
        function expandTree() {
            console.log("Expanding All...");
            var tree = $("#treeview").data("kendoTreeView");
            var nodes = document.getElementsByClassName('k-item');
            for (var i = 0; i < nodes.length; i++) {
                expandNode(nodes[i]);
            }
        }

        // Expand nodes recursively
        function expandNode(htmlElement) {
            var tree = $("#treeview").data("kendoTreeView");
            var dataItem = tree.dataItem(htmlElement);
            dataItem.set("expanded", true);
            var children = dataItem.items;
            if (children) {
                for (var i = 0; i < dataItem.items.length; i++) {
                    expandNode(tree.findByUid(dataItem.items[i].uid))
                }
            }
        }