a javascript string problem?

i have this script, but i the result.bgimage is not showing up, i think JS thinks its a string rather th开发者_JS百科an variable!!! how can i solve this problem? thanks

$('#bg')
    .animate({opacity: 0}, 'slow', function() {
        $(this)
            .css({'background-image': 'url(result.bgimage)'})
            .animate({opacity: 1});
    });

$('#bg')
    .animate({opacity: 0}, 'slow', function() {
        $(this)
            .css({'background-image': 'url(' + result.bgimage + ')'})
            .animate({opacity: 1});
    });