today=new Date();  
var cmas=new Date(today.getFullYear(), 11, 25);  
if (today.getMonth()==11 && today.getDate()>25)   
{  
cmas.setFullYear(cmas.getFullYear()+1);   
}    
var one_day=1000*60*60*24;  
console.log(Math.ceil((cmas.getTime()-today.getTime())/(one_day))+  
" days left until Christmas!");