javascript - How can I get a webpage to display once and never show to the user again?

Question

Im currently using a javascript code to check for a cookie and its working. But I want the user to be directed to another page once they have entered in their user ID (cookie). Is there another function that I can add so that the user can be directed to another page once I have the cookie? The code is set up where they wont see this window for a year.

I'm not sure what to add. Please help.

<script>
function getCookie(c_name) {
    var c_value = document.cookie;
    var c_start = c_value.indexOf(" " + c_name + "=");
    if (c_start == -1) {
        c_start = c_value.indexOf(c_name + "=");
    }
    if (c_start == -1) {
        c_value = null;
    } else {
        c_start = c_value.indexOf("=", c_start) + 1;
        var c_end = c_value.indexOf(";", c_start);
        if (c_end == -1) {
            c_end = c_value.length;
        }
        c_value = unescape(c_value.substring(c_start, c_end));
    }
    return c_value;
}

function setCookie(c_name, value, exdays) {
    var exdate = new Date();
    exdate.setDate(exdate.getDate() + exdays);
    var c_value = escape(value) + ((exdays == null) ? "" : "; expires=" + exdate.toUTCString());
    document.cookie = c_name + "=" + c_value;
}

function checkCookie() {
    var username = getCookie("username");
    if (username != null && username != "") {
        alert("Welcome again " + username);
    } else {
        username = prompt("Please enter your name:", "");
        if (username != null && username != "") {
            setCookie("username", username, 365);
        }
    }
}
</script>

Answer 1

if(localStorage.beenHere){
  //Been here before
}else{
  localStorage.beenHere = 1;
}