Age Popup

<script>
function setCookie(cname, cvalue, exdays) {
    var d = new Date();
    d.setTime(d.getTime() + (exdays*24*60*60*1000));
    var expires = "expires="+d.toUTCString();
    document.cookie = cname + "=" + cvalue + "; " + expires;
}

function getCookie(cname) {
    var name = cname + "=";
    var ca = document.cookie.split(';');
    for(var i=0; i<ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1);
        if (c.indexOf(name) != -1) return c.substring(name.length, c.length);
    }
    return "";
}
var agecookie = getCookie("age");

if (agecookie != "true"){
var age = prompt("How old are you?");
//check the age of the user and produces proper output
document.write(agecookie);

if (age >= 18)
{
    alert("YOU CAN CONTINUE");
	setCookie("age","true",2);
}
else
{
    window.location.replace("http://google.com");
}
}
</script>