The source code

    Ext.onReady(function(){
        // shorthand
        var Tree = Ext.tree;

        var tree = new Tree.TreePanel({
            useArrows: true,
            autoScroll: true,
            animate: true,
            enableDD: true,
            containerScroll: true,
            border: false,
            // auto create TreeLoader
            dataUrl: 'get-nodes.php',

            root: {
                nodeType: 'async',
                text: 'Ext JS',
                draggable: false,
                id: 'src'
            }
        });

        // render the tree
        tree.render('tree-div');
        tree.getRootNode().expand();
    });