Using Cookies to set an alert in javascript

JavaScript

(function checkCookie()
{
var username=getCookie("username");
if (username!=null && username!=""){
    alert("Welcome again "+ username);

}
else {
    username=prompt("Please input name:","");
    if (username !=null && username!="")
    {
        setCookie("username", username, 365);
    }
    else{
    alert("Error");
    }
}

}) ();
function setCookie (cname,cvalue,exdays)
{
    var d = new Date();
    d.setTime (d.getTime()+ (10*1000));
    var expires ="; expires= "+ d.toUTCString();
    document.cookie = cname + "=" + cvalue + "; " + expires; +"; path /";
}
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) == 0){
        return c.substring(name.length, c.length);
        }
    }
return "";
}