title: how to add children to existing array in javascript
body: <p>I have an array in javascript:</p>
  
  <pre><code>var elements = [ // original hierarhical array to display
              {key:10, label:"Web Testing Dep.", open: true, children: [
                  {key:20, label:"Elizabeth Taylor"},
                  {key:30, label:"Managers",  children: [
                      {key:40, label:"John Williams"},
                      {key:50, label:"David Miller"}
                  ]},
                  {key:60, label:"Linda Brown"},
                  {key:70, label:"George Lucas"}
              ]},
              {key:110, label:"Human Relations Dep.", open:true, children: [
                  {key:80, label:"Kate Moss"},
                  {key:90, label:"Dian Fossey"}
              ]}
          ];
  </code></pre>
  
  <p>If I want to add a whole new element I can use a <code>push()</code>. But I want to add a part of an element.
  for exemple I want to add</p>
  
  <pre><code>var toAdd = {key:100, label:"Johny Dep"}
  </code></pre>
  
  <p>To the children of key 10 "web testing dep.". 
  Is it also possible with a <code>push()</code>?</p>