Unable to export to dropbox

Hi, I wat to upload my file to dropbox in nodejs but its not working.

var options = {"exportURL":"dropbox://"};
client.html_to_pdf(`"${html_document}"`, options);
client.save("http://www.example.com/handler", function (error, id){
if (error != null){
throw error;
    }
    console.log(id);
 });

i just want to upload my file to created pdf directly to dropbox but this is not working. Can you help me out.

Thanks,