function calculateage(birthyear,currentyear)
    {
     var age=currentyear-birthyear;
     console.log("you are either '+age+' or '+(age-1)+');
    }
    var d = new Date();
    var n = d.getFullYear();
    calculateage(1995,2017);
    calculateage(1994,2015);
    calculateage(1997,2000);