Develop Reference

Check for Cookie existance, if yes do whatever, if no set a cookie

So what im tryin to do is to check for a cookie existance (for example accepted=yes) If it is not set, it will return nothing and if not, it will execute some script and set the accepted=yes cookie. So that on the next visit the visitor wont see the popup.
var cookie = document.cookie;
if (cookie = accepted=yes) {
} else {
document.cookie = "accepted=yes";
}
That is the code i have discovered.

You can use getCookie and setCookie 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 "";
}
Example
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);
}
}
Reference: W3Schools https://www.w3schools.com/js/tryit.asp?filename=tryjs_cookie_username

Website not getting cookie info correctly and spamming reload

I'm trying to define a version for my website so it can reload the resources if the versions don't match. The problem is that when I fetch the cookie, the cookie value is not returned. The result of this is that the website is in a constant state of reloading.
I made sure that the cookie was there and I tried using my functions in the console and setting the cookie manually.
Webpage:
var version = '1.0.0';
var cVersion = version == getCookie("version");
if(!cVersion) {
setCookie("version", version, 1000);
window.location.reload(true);
}
Cookies 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 + ";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 "";
}
The website should reload and update the version number if they are different and do nothing if they are the same.

Setting session variable in Javascript response

I was wondering if there is a way to set session variable in Ajax response, which would basically look like this:
// this is response
function(response)
{
<?php $_SESSION['ID'] = response.id ?>
// or something similar to this?
}
And then afterwards when I need to use the session so that I can access it.
// (Some php file)
$var_id = $_SESSION['ID'];
Is this doable?

Here are three functions to set, get, and delete cookies
https://jsfiddle.net/stevenkaspar/gnoj9aop/
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 deleteCookie(cname){
document.cookie = cname+"=; expires=Thu, 01 Jan 1970 00:00:00 UTC";
}

You can use HTML5 sessionStorage Object to save the data locally but for a single session . The data is deleted when the user closes the specific browser tab.
sessionStorage.id = response.id ;

Can I define JavaScript global variables to use across multitple pages?

I want to define a global variable in JavaScript that I can use across multiple html pages. Please suggest.

This is not possible instead you can use cookies to store the variables and retrive them in another html pages.
Use this function to set your cookies
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;
}
and use this function to retrive cookies
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 "";
}

cookie is expired when browser closed for a html file locating on harddrive

It is a html file with Javascript which is located on my computer (not real home page).
I am using following JavaScript code to add a cookie, the cookie is stil alive when I don't close the browser but when I close the browse the cookie does not exist any more. How do I make the cookie survive in 4 days even when you close the browser?
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;
}
setCooike("name", "test", 4);
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 "";
}
getCookie("name") returns ""??

This is likely a setting in your browser to clear your cookies when you close it. So it cannot be resolved by code, some users will have this setting enabled and won't want to use cookies so you should plan for that situation.