code: function parsePropertyValue (node) {
      var $node = $(node);
  
      if ($node.is('meta')) {
        return resolveAttribute($node, 'content');
      } else if ($node.is('audio,embed,iframe,img,source,track,video')) {
        return resolveUrlAttribute($node, 'src');
      } else if ($node.is('a,area,link')) {
        return resolveUrlAttribute($node, 'href');
      } else if ($node.is('object')) {
        return resolveUrlAttribute($node, 'data');
      } else if ($node.is('data,meter')) {
        return resolveAttribute($node, 'value');
      } else if ($node.is('time')) {
        return resolveAttribute($node, 'datetime');
      } else {
        var text = $node.text();
        return text || '';
      }
    }
docs: extracts the property value out of an itemprop DOM node