Age Calculation from Date of Birth Using Javascript/Jquery

Many times we want to allow users to enter site only if they are of 18 years of age, or while registering we ask DOB and we need to calculate their age if they are eligible or not. Here is the javascript function to calculate age based on DOB.

Method 1:

<script type="text/javascript">
	function CalAge() {

    var now = new Date();
    var mm = document.getElementById('ddlmnths').value;
    var ddr = document.getElementById('ddldays');
    var dd = ddr.options[ddr.selectedIndex].value;
    var yy = document.getElementById('ddlyrs').value;
    bDay = dd + "/" + mm + "/" + yy;
    bD = bDay.split('/');
   	    if (bD.length == 3) {
        	   born = new Date(bD[2], bD[1] * 1 - 1, bD[0]);
                 years = Math.floor((now.getTime() - born.getTime()) / (365.25 * 24 * 60 * 60 * 1000));
        if (years < 18) {
            alert(“You are not eligible”);

        }
        else if (years = 18 || years > 18) {
        	alert(“Welcome”);
        }
    }
}
</script>

Method 2 :

<script type="text/javascript">

     function CalAge() {
     var dd = $("#ddldays").val();
     var mm = $("#ddlmnths").val();
     var yy = $("#ddlyrs").val();
     var age = 18;

     var mydate = new Date();
     mydate.setFullYear(yy, mm-1, dd);

     var currdate = new Date();
     currdate.setFullYear(currdate.getFullYear() - age);
     if ((currdate - mydate) < 0){
     alert(“You are not eligible”);
     }
     else
    {
	alert(“Welcome”);
    }
   }
</script>