<div id="grid"></div>
<script>
    $("#grid").kendoGrid({
        contextMenu: {
            body: [
                {
                    text: "Custom Command",
                    icon: "calendar",
                    items: [
                        { text: "Nested Custom Command", icon: "home", command: "NestedCustomCommand" }
                    ]
                },
                'select'
            ]
        },
        dataSource: new kendo.data.DataSource({
            schema: {
                model: {
                    id: "foo",
                    fields: {
                        name: "name",
                        foo: "foo",
                    },
                },
            },
            data: [
                { foo: "bar", name: "tom" },
                { foo: "baz", name: "jerry" },
            ],
        }),
    });

    kendo.ui.grid.commands["NestedCustomCommand"] = kendo.ui.grid.GridCommand.extend({
        exec: function(e) {
             alert("Custom Command Executed")
        }
    });
</script>