I'm trying to get the name of the clicked node from jstree

I'm not good in ajax I'm trying this way that I found but is not working, and i don't know from where the problem come

folderTreeView = $(".folderpreview");
        var datanew = JSON.parse(data)
        // Files Treeview
        if (folderTreeView.length) {
          folderTreeView.jstree({
            core: {
              themes: {
                dots: false,
              },
              data: datanew.children,
            },
            plugins: ["types"],
            types: {
              default: {
                icon: "far fa-folder font-medium-1",
              },
              ".jpg": {
                icon: "far fa-file-image text-info font-medium-1",
              },
              ".docx": {
                icon: "far fa-file-word text-info font-medium-1",
              },
              ".pdf": {
                icon: "far fa-file-pdf text-info font-medium-1",
              },
            },
          });

          folderTreeView
            .on("changed.jstree", function (e, data) {
              var i, j, r = [];
              for (i = 0, j = data.selected.length; i < j; i++) {
                r.push(data.instance.get_node(data.selected[i]).name);
              }
              $("#event_result").html("Selected: " + r.join(", "));
            })
            .jstree({
              core: {
                data: {
                  url: function (node) {
                    return node.id === "#" ? "./ajax_roots.json" : "./ajax_children.json";
                  },
                  data: function (node) {
                    return { 'id' : node.id};
                  },
                },
              },
            });
        }