title: JSON.stringify(object) incorrect
body: <p>Sorry for my last question being so confusing, I was confused my self, but now I got a proper example:</p>
  
  <pre><code>var obj = {};
  obj.entities = [];
  obj.entities["player"] = [];
  obj.entities["player"]["0"] = [];
  obj.entities["player"]["0"]["pos"] = "0,0";
  
  var jsonStr = JSON.stringify(jsonObj);
  
  // {"entities":[]}
  console.log(JSON.stringify(obj));
  </code></pre>
  
  <p>The output of <code>JSON.stringify(obj)</code> is wrong as you can see.
  What causes this ?</p>