title: how to append json variable as child nodes using "jstree" jquery plugin - no ajax
body: <p>I have a jsTree using the json data format. 
  Loading the root nodeset is fine.</p>
  
  <p>My problem is how to append child nodes to the parent node that was clicked.</p>
  
  <p>ANY help would be appreciated.</p>
  
  <p>Thanks!</p>
  
  <pre><code>    $("#tree-cat1")
      .bind("open_node.jstree", function (event, data) {
          console.log(data.rslt.obj.attr("id"));
          //eval(loadChild());
          //at this point i need to append the result of loadChild() to the tree under the relevant node
      })
      .jstree({
          "json_data": {
              "data": eval(loadRoot())
          },
          "themes": {"theme": "classic","dots": true,"icons": true},
          "plugins": ["themes", "json_data", "ui"]
      })
  
  function loadRoot() {
      return "[{'data':'A node','state':'closed','attr':{'id':'A'}}]";
  }
  function loadChild() {
      return "[{'data':'A1 node','attr':{'id':'A1'}}]";
  }
  </code></pre>