var booking = 
{
    changeNumberOfChildren: function( element )
    {
        var number = element.value;
        $('div.bk-child').hide();
        for ( var i = 1; i <= number; i++ )
        {
            $('div#bk-child-' + i).show();
        }
    }
}

$( function()
{
    $('input.datepicker').datepicker( { dateFormat: 'dd.mm.yy' } );
} );