ColumnShow

<div id="treeList"></div>
<script>
  $("#treeList").kendoTreeList({
    columns: [
      { field: "id" },
      { field: "name" },
      { field: "age" }
    ],
    dataSource: {
      data: [
        { id: 1, parentId: null, name: "Jane Doe", age: 22 },
        { id: 2, parentId: 1, name: "John Doe", age: 24 }
      ]
    },
    columnMenu: true,
    columnShow: function(e) {
/* The result can be observed in the DevTools(F12) console of the browser. */
      console.log(e.column.field); // displays the field of the shown column
    }
  });
</script>

<div id="treeList"></div>
<script>
  function treelist_columnShow(e) {
/* The result can be observed in the DevTools(F12) console of the browser. */
    console.log(e.column.field); // displays the field of the shown column
  }

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

  var treelist = $("#treeList").data("kendoTreeList");
  treelist.bind("columnShow", treelist_columnShow);
</script>