The JS implementation calculates the age based on the date of birth
<script language=javascript> function ages(str) { var r = str.match(/^(d{1,4})(-|/)(d{1,2})2(d{1,2})$/); if(r==null)return false; var d= new Date(r[1], r[3]-1, r[4]); if (d.getFullYear()==r[1]&&(d.getMonth()+1)==r[3]&&d.getDate()==r[4]) { var Y = new Date().getFullYear(); return(" age = "+ (Y-r[1]) +" One full year of life "); } return(" Wrong date format! "); } alert(ages("1980-03-22")); alert(ages("2002-01-31")); alert(ages("2002-01-41")); </script>