Develop Reference

Run script with timeout once per session (but you could reload page and go to another page)

I've got a simple script, that I need to run only once per session of user. But in this session he could refresh page, or go to another page on one site.
My code now looks like this, but if user refresh page (in less then 10 seconds) or go to another page - script will never run :(
var visited = sessionStorage.getItem('visit');
if (visited == null || document.location.href == sessionStorage.getItem('lastPage')) {
setTimeout(function() {
alert('Hello World')
}, 10000
)
sessionStorage.setItem('visit', 1);
};
Working example: https://codepen.io/zavtraleto/pen/GdRpRZ
I think it's something with cookies, maybe

I made it using cookie, so if everyone interested:
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) == 0) {
return c.substring(name.length, c.length);
}
}
return "";
}
function checkCookie() {
var user = getCookie("username");
if (user != "") {
alert("Welcome again " + user);
} else {
user = prompt("Please enter your name:", "");
if (user != "" && user != null) {
setCookie("username", user, 365);
}
}
}
getCookie('user_first_visited') || setCookie('user_first_visited', Date.now());
if (!getCookie('user_popup_triggerred')) {
var loopDetect = setInterval(function(){
var TimePast = (Date.now() - getCookie('user_first_visited')) / 1000;
if( TimePast > 5){
if (localStorage.getItem('surveyOnce') !== 'true') {
(function() {
alert('Hello World!')
}
)();
localStorage.setItem('surveyOnce','true');
};
}
}, 1000);
}

How to make an if statement that checks if a cookie is expired

I have a program that needs to check for a cookie. When the cookie expires, I want it to display a prompt and alert something.
if (document.cookie == '' || document.cookie == null || document.cookie == undefined) {
var site = prompt("Please enter a valid url:", "http://");
document.cookie = "url=;"
document.cookie = 'expires=Thu, 01 Jan 2030 00:00:00 GMT';
alert("The cookie is expired.");
}
But it doesn't seem to work.

if you search on google you will easily find some basic get/set functions,
Here is a sample link
function getCookie(cname) {
var name = cname + "=";
var decodedCookie = decodeURIComponent(document.cookie);
var ca = decodedCookie.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 "";
}
then you could use this as below
if(getCookie(nameOfYourCookie) == "")
{
//Show Alert,
//Set cookie
}

javascript counter with cookies doesn't work

I just tried to make a timer with cookies that makes a button only 3 times clickable (I had to do it with cookies cause it refreshes the page in its process), I made this timer but it doesn't work. Nothing on my page changed at all.
The code I have by //something else happens gets executed by the program.
Timer - (or at least what I thought that would work as a timer) :
mailagain.onclick = function () {
if (typeof getCookie("countIt") !== 'undefined') {
if (checkCookie("countIt") > 3) {
// something happens
} else {
//something else happens
var counter = checkCookie("countIt") + 1;
setCookie("countIt", counter, 1)
}
} else {
setCookie("countIt", 1, 1)
}
};
Coockie functions :
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 + ";path=/";
}
function getCookie(cname) {
var name = cname + "=";
var decodedCookie = decodeURIComponent(document.cookie);
var ca = decodedCookie.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 "";
}
function checkCookie(name) {
var value = getCookie("name");
if (value != "") {
return value;
}
}

Some issues:
When reading the value from the cookie, be aware that it has the string data type. You need to convert it to number before comparing it with another number or adding 1 to it.
The function checkCookie is using the wrong (hard-coded) cookie name, but is even not necessary as a function. You can do all that with getCookie.
Here is a working version:
mailagain.onclick = function () {
// make sure to convert to number (unitary plus), or use 0 when it is not a number:
var counter = (+getCookie("countIt") || 0) + 1;
setCookie("countIt", counter, 1)
if (counter > 3) {
console.log('clicked too many times! (', counter, ')');
} else {
console.log('clicked ' + counter + ' number of times.');
}
};

var value = getCookie("name");
getCookie always return "undefined" because of wrong cookie name. Remove brakets.
function checkCookie(name) {
var value = getCookie(name); //here you go
if (value != "") {
return value;
}
}

How do I get a cookie from user input, and display it on an html element

I'm making a website that uses a cookie to get the user's name. When I try to get it to be shown with inner.html, it won't even prompt the user. Here is my code. The area is specific is the function checkCookie()
<!DOCTYPE html>
<html>
<head>
<script>
function setCookie(cname,cvalue,exdays) {
var d = new Date();
d.setTime(d.getTime() + (exdays*24*60*60*1000));
var expires = "expires=" + d.toGMTString();
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) == 0) {
return c.substring(name.length, c.length);
}
}
return "";
}
function checkCookie() {
var user=getCookie("username");
if (user != null) {
document.getElementById("person").innerHTML =
"Hello " + user + "!";
} else {
user = prompt("Please enter your name:","");
if (user != "" && user != null) {
setCookie("username", user, 30);
}
}
}
</script>
</head>
<body onload="checkCookie()">
<p id="person">anonymous user</p>
</body>
</html>

Change
return "";
to:
return null;
checkCookie expects getCookie to return null when the cookie isn't found. An empty string is not the same as null.
DEMO

Pop up once every 30 days

I am totally novice for JS and cookies. I got this code online and tried to change it for 30 days (it was set to 365) but it's probably resetting the cookie for every page and the pop up appears if I go to other page or even return back to the original page. Only things I changed in the code was expire days to 30 and load delay of 30 secs.
It seems either it's resetting the cookie every time I move to other page or some other problem which I don't understand yet :). I was wondering if there is some more efficient way to have it rather putting the code in every html article page. Something like setting up a cookie in headers or something and recalling using body onload.
Here is the code:
<SCRIPT language=JavaScript>
<!--
var expDays = 30; // number of days the cookie should last
function GetCookie (name) {
var arg = name + "=";
var alen = arg.length;
var clen = document.cookie.length;
var i = 0;
while (i < clen) {
var j = i + alen;
if (document.cookie.substring(i, j) == arg)
return getCookieVal (j);
i = document.cookie.indexOf(" ", i) + 1;
if (i == 0) break;
}
return null;
}
function SetCookie (name, value,expires) {
var argv = SetCookie.arguments;
var argc = SetCookie.arguments.length;
var expires = (argc > 2) ? argv[2] : null;
var path = (argc > 3) ? argv[3] : null;
var domain = (argc > 4) ? argv[4] : null;
var secure = (argc > 5) ? argv[5] : false;
document.cookie = name + "=" + escape (value) +
((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +
((path == null) ? "" : ("; path=" + path)) +
((domain == null) ? "" : ("; domain=" + domain)) +
((secure == true) ? "; secure" : "");
}
function DeleteCookie (name) {
var exp = new Date();
exp.setTime (exp.getTime() - 1);
var cval = GetCookie (name);
document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}
var exp = new Date();
exp.setTime(exp.getTime() + (expDays*24*60*60*1000));
function getCookieVal(offset) {
var endstr = document.cookie.indexOf (";", offset);
if (endstr == -1)
endstr = document.cookie.length;
return unescape(document.cookie.substring(offset, endstr));
}
function checkCount() {
var count = GetCookie('poponce');
if (count == null) {
count++;
SetCookie('poponce', count, exp);
// Action to take
dothis()
}
}
setTimeout(function dothis(){
var windowprops = "left=300,top=240,width=600,height=400,location=no,toolbar=no,menubar=no,scrollbars=no";
window.open("/subscribepopup.html", "", windowprops); // Use to load a page
}, 30000);
// -->
</SCRIPT>
<body OnLoad="checkCount()">