extjs tree的问题，希望有人可以解答~~

   Ext.onReady(function(){ 
            Ext.QuickTips.init(); 

        var treeLoader = new Ext.tree.TreeLoader({
        dataUrl:'/s2shDemo/js/01.txt'
    });
    var rootNode = new Ext.tree.AsyncTreeNode({
        text: 'Root'
    });
        var tree = new Ext.tree.TreePanel({
        renderTo:'treecontainer',
        loader: treeLoader,
        root: rootNode,
        enableDD: true
    });
    


    
    //移动节点
        tree.on('beforemovenode', function(tree, node, oldParent, newParent, index) {
        Ext.Ajax.request({
            url: 'http://localhost/node-move.php',
            params: {
                nodeid: node.id,
                newparentid: newParent.id,
                oldparentid: oldParent.id,
                dropindex: index
            }
        });
    });
            tree.setRootNode(root); 
            tree.render();                      
                       
        });