[destus]

jack3dm,

var diff = 15,
            a = new Date("17 March 2016 11:13:00 UTC");
            b = new Date("17 December 2015 11:13:00 UTC");
        Math.round((Date.now() - a) / (1000 * 60 * 60 * 24) > diff) ? alert('yes') : alert('no');
        Math.round((Date.now() - b) / (1000 * 60 * 60 * 24) > diff) ? alert('yes') : alert('no');