for (var i = 0; i < data.features.length; i++)
  {
        var precio = parseFloat(data.features[i].properties.precio);
        if (precio != '')
           precio = '$' + precio.toFixed(0).replace(/(d)(?=(ddd)+(?!d))/g, "$1,");
         else
          precio = 'Sin precio';

        h += '<div class="col-lg-6 col-md-6 col-sm-12 col-xs-12 propDetails"' +
        'style="background-image: url('ruta/images/'+ data.features[i].properties.id +'/foto_principal.jpg')">' +
            '<img class="fav" src="../images/favorito.png">' +
              '<div class="details">' +
                  '<p class="dom"><span>'+ precio +'</span><br>'+ data.features[i].properties.calle +'</p>' +
              '</div>' +
        '</div>';
  }

.propDetails
{
  background-image: url(../images/default.png);
}