extjs 3.31 TreeGrid implements static page loading json into TreeGrid_extjs

var root = new Ext.tree .TreeNode({
text: 'Root node',
expanded: true
});
tree.setRootNode(root);
var nodes = {};
nodes. children = mydata;/*TreeGrid’s json data [{…},{…}]*/
function appendChild(node, o) {
if (o.children != null && o.children. length > 0) {
for (var a = 0; a < o.children.length; a ) {
var n = new Ext.tree.TreeNode({
task:o.children [a].task,
duration:o.children[a].duration,
user:o.children[a].user,
iconCls:o.children[a].iconCls
});
node.appendChild(n);
appendChild(n, o.children[a]);
}
}
}
appendChild(root, nodes);