Management of the jit.js library with json

Look, I have a .js file that loads a json and is working. In principle you will be charged a% full% co, and then doing json expands the children of the clicked node:

• When the page loads:

  //load json data
  st.loadJSON(json);
  //compute node positions and layout
  st.compute();
  //optional: make a translation of the tree
  st.geom.translate(new $jit.Complex(-200, 0), "current");
  //emulate a click on the root node.
  st.onClick(st.root);
  //end
  

• When a click is made on the node:

  onCreateLabel: function(label, node){
      label.id = node.id;            
      label.innerHTML = node.name;
      label.onclick = function(){
          st.onClick(node.id);
      };
  

I have introduced a modification, so that at first a click is loaded and then a larger one when clicking on a node:

 onCreateLabel: function(label, node){
        label.id = node.id;            
        label.innerHTML = node.name;
        label.onclick = function(){

        var http = new XMLHttpRequest();
        var url = "inicio_pru.php";
        var params = "callFunction=arbol_completo";
        http.open("POST", url, true);
        //Send the proper header information along with the request
        http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        http.send(params);
        http.onreadystatechange = function() {//Call a function when the state changes.
                    if(http.readyState == 4 && http.status == 200) {

                             json=http.responseText;
                             st.loadJSON(json);
                              //compute node positions and layout
                             st.compute();
                              //optional: make a translation of the tree
                             st.geom.translate(new $jit.Complex(-200, 0), "current");
                             //emulate a click on the root node.
                             st.onClick(node.id);
                      }
            };

The page load is correct, but when I click on the label of a node, I get the following error:

  

jit.js: 8795 Uncaught TypeError: Can not read property 'id' of undefined

The json is like this:

'{"id":"38358","name":"Anillo Critico","data":{"$color":"#008000","$type":"circle"},"children":[]}';    

With what I deduce that when doing json , a node is created with a st.loadJSON(json) , a id and a name , and one is created for each data of id . When I do json in one, I send click the st.onClick(node.id) of that in particular.

Can you help me? Thank you very much in advance.