title: OL3: extracting 'extended data' from KML
body: <p>i have created a KML file with some custom attributes such as 'id' and 'room_id'.</p>
  
  <p>these attributes exist in the 'extended data' part of the KML file, here is the file:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
  &lt;kml xmlns="http://www.opengis.net/kml/2.2"&gt;
  &lt;Document id="root_doc"&gt;
  &lt;Schema name="map" id="map"&gt;
      &lt;SimpleField name="id" type="int"&gt;&lt;/SimpleField&gt;
      &lt;SimpleField name="room_id" type="string"&gt;&lt;/SimpleField&gt;
  &lt;/Schema&gt;
  &lt;Folder&gt;&lt;name&gt;map&lt;/name&gt;
    &lt;Placemark&gt;
      &lt;name&gt;room1&lt;/name&gt;
      &lt;Style&gt;&lt;LineStyle&gt;&lt;color&gt;ff0000ff&lt;/color&gt;&lt;/LineStyle&gt;&lt;PolyStyle&gt;&lt;fill&gt;0&lt;/fill&gt;&lt;/PolyStyle&gt;&lt;/Style&gt;
      &lt;ExtendedData&gt;&lt;SchemaData schemaUrl="#map"&gt;
          &lt;SimpleData name="id"&gt;2&lt;/SimpleData&gt;
          &lt;SimpleData name="room_id"&gt;1&lt;/SimpleData&gt;
      &lt;/SchemaData&gt;&lt;/ExtendedData&gt;
        &lt;Polygon&gt;&lt;altitudeMode&gt;relativeToGround&lt;/altitudeMode&gt;&lt;outerBoundaryIs&gt;&lt;LinearRing&gt;&lt;altitudeMode&gt;relativeToGround&lt;/altitudeMode&gt; &lt;coordinates&gt;-0.000010931306469,0.000006764422322 -0.000004193941839,0.000006764422322 -0.000004166884149,0.00000037880765 -0.000010985421848,0.00000043292302 -0.000010931306469,0.000006764422322&lt;/coordinates&gt;&lt;/LinearRing&gt;&lt;/outerBoundaryIs&gt;&lt;/Polygon&gt;
    &lt;/Placemark&gt;
  &lt;/Folder&gt;
  &lt;/Document&gt;&lt;/kml&gt;
  </code></pre>
  
  <p>i am trying to access these attributes using OL3 but can't figure it out. here is the code i use to access the standard KML properties 'name' and 'description':</p>
  
  <pre><code>vector.getSource().forEachFeature(function (feature) {
  
       var desc = feature.getProperties()['description'];
       console.log(desc);
  
       var name = feature.getProperties()['name'];
       console.log(name);
  
  });
  </code></pre>
  
  <p>how do i access the 'extended data' properties of a KML file with OL3?</p>
  
  <p>thanks!</p>