Develop Reference

How to check if an element has a class using PHP in Wordpress function.php file

I am trying to hide an element on the front-end and remember the user choice by creating a cookie in PHP.
Here is how I have it set up:
I have some HTML and JS scripts inside an HTML widget on the page on the front-end
<div id="training-banner"> training banner design here </div>
<button onclick="myFunction()" id="close-btn">X</button>
<script>
function myFunction() {
var element = document.getElementById("training-alert");
element.classList.add("hidebanner");
}
</script>
Then I have written the cookie function inside the function.php of the child theme:
add_action('init', function() {
if (!isset($_COOKIE['training_banner_cookie'])) {
setcookie('training_banner_cookie', 'showbanner', strtotime('+1 day'));
}
if (class_exists('hidebanner')){
?><style>#training-alert{display:none;}</style> <?php
setcookie('training_banner_cookie', 'hidebanner', strtotime('+1 day'));
}
$cookieValue = $_COOKIE['training_banner_cookie'];
if ($cookieValue == "hidebanner"){
?><style>#training-alert{display:none;}</style> <?php
}
});
For some reason, the class_exists() PHP function does not work, any idea how this can be achieved?

https://www.php.net/manual/en/function.class-exists.php
class-exists is not used in your case. It is used to check if a Class exists in your PHP code block.
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
What you want to do is to save the choice of the users' choice. You can simply use JS to achieve it.
<div id="training-banner"> training banner design here </div>
<button onclick="myFunction()" id="close-btn">X</button>
<script>
function getCookie(cookieName: string, cookie?: string): string {
const name = cookieName + '='
const decodedCookie = decodeURIComponent(cookie || document.cookie)
const ca = decodedCookie.split(';')
for (let i = 0; i < ca.length; i++) {
let 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 setCookie(
cookieName,
value,
days,
isSecure = true
): void {
let expires = ''
const secure = isSecure ? '; Secure' : ''
if (days) {
const date = new Date()
date.setTime(date.getTime() + days * 86400000)
expires = ' ;expires=' + date.toUTCString()
}
document.cookie = cookieName + '=' + value + expires + ' ;path=/' + secure
}
function myFunction() {
var element = document.getElementById("training-alert");
element.classList.add("hidebanner");
setCookie('training_banner_cookie_hide', true, 1)
}
function init(){
var shouldHideBanner = getCookie('training_banner_cookie_hide')
if(shouldHideBanner){
var element = document.getElementById("training-alert");
element.style.display = 'none';
}
}
init()
</script>

With the help of #WillyLi's answer, I was able to organize my thoughts and modify his code a bit here is what worked for me:
I modified the getCookie function declaration and simplified it to one parameter cname.
Then I also modified the setCookie and standardized it according to w3school
Finally, I wanted the banner to be hidden immediately as the user clicks the button so I added element.style.display = 'none'; to myFunction()
Here is what the final version looks like:
<button onclick="myFunction()" id="close-btn">X</button>
<script>
function getCookie(cname) {
let name = cname + "=";
let decodedCookie = decodeURIComponent(document.cookie);
let ca = decodedCookie.split(';');
for(let i = 0; i <ca.length; i++) {
let 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 setCookie(cname, cvalue, exdays) {
const d = new Date();
d.setTime(d.getTime() + (exdays*24*60*60*1000));
let expires = "expires="+ d.toUTCString();
document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
}
function myFunction() {
var element = document.getElementById("training-alert");
element.style.display = 'none';
setCookie('training_banner_cookie_hide', true, 1);
}
function init(){
var shouldHideBanner = getCookie('training_banner_cookie_hide');
if(shouldHideBanner){
var element = document.getElementById("training-alert");
element.style.display = 'none';
}
}
init()
</script>

Set cookie in MTurk HIT

I recently had issues using javascript cookies inside an MTurk HIT. In particular I'm trying to track user preferences w.r.t showing/hiding the HIT instruction.
My approach so far is the following:
<body>
<div id='instructionButton'>
<!-- Button triggering instruction body to collapse/show -->
</div>
<div id='instructionBody'>
<!-- Instruction content (collapsible) -->
...
</div>
</body>
<script>
const instructionBodyId = 'instructionBody';
const instructionButtonId = 'instructionButton';
const cookieName = 'my_cookie_name';
var isInstructionShown = true;
var instrContent = $('#' + instructionBodyId);
var instrButton = $('#' + instructionButtonId);
function setCookie(name, value) {
var date = new Date();
<!-- Cookie valid for 48h -->
date.setTime(date.getTime() + (48 * 60 * 60 * 1000));
var expires = "; expires=" + date.toUTCString();
document.cookie = name + "=" + value + expires + "; path=/";
}
function getCookie(name) {
var nameEQ = name + "=";
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, c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
}
return null;
}
function toggleInstructions(isShow) {
setCookie(cookieName, isShow);
isInstructionShown = isShow;
if (isShow) {
instrContent.slideDown();
} else {
instrContent.slideUp();
}
}
function prepare_cookie() {
instrButton.click(function() {
toggleInstructions(!isInstructionShown);
});
let cookieVal = getCookie(cookieName);
if (cookieVal == "false") {
toggleInstructions(false);
} else {
toggleInstructions(true);
}
}
$(document).ready(function() {
prepare_cookie();
});
</script>
The code above shows part of the HIT layout I'm creating, and when testing it out while editing the HIT directly in MTurk, the cookie works as expected (it shows up in Google Chrome and works as expected, showing/hiding the instruction automatically).
Unfortunately, when publishing the HIT, the cookie does not seem to be set (it does not appear in the list of cookies shown in Google Chrome).

Language switcher - Javascript/jQuery and Cookies

Using both internet and Stack Overflow resources I managed to write a crude HTML website, that allows the user to switch Language of it on the fly, using Javascript, jQuery and XML.
Now, the problem I ran into is to keep the preferred language across the entire portal, without the need to change it each time when navigating through it. I have decided to use a simple cookie to keep the track of it, but it seems I have messed something up, and I can't figure out what I'm doing wrong.
Basically speaking, the page itself has text in the code itself (as a backup just in case), however the text becomes invisible when booting the site, until I switch a language, nor the language is kept when I navigate the portal. For the former, I assumed that the script was reading some empty or overall wrong cookie, so I made an attempt to filter it out and use a default language, but in vain. As for the latter issue, I guess I save the cookie itself wrong as well, but I can't seem to figure out what's wrong with it.
Any help/advice would be appreciated.
function changeLanguage(lang) {
$(function() {
$.ajax({
url: 'jezyki.xml',
success: function(xml) {
$(xml).find('translation').each(function(){
var id = $(this).attr('id');
var text = $(this).find(lang).text();
$("." + id).html(text);
if (lang === "") { }
else {
var title = lang;
createCookie("language", title, 365);
}
});
}
});
});
}
$(document).ready(function () {
$("input[name='radio-language']").click(function () {
changeLanguage($(this).val());
});
});
function createCookie(name, value, days) {
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
var expires = "; expires=" + date.toGMTString();
}
else expires = "";
document.cookie = name + "=" + value + expires + "; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
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, c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
}
return null;
}
window.onload = function (e) {
var cookie = readCookie("language");
var domyslny = "english";
if (title === "") { changeLanguage(domyslny); } else { changeLanguage(title); }
}
Apologies if this is something silly, I am quite a newbie when it comes to Javascript/jQuery.

create and save cookies on onclick

Can anyone help me set up a cookie function that can take user input by checking which link the user clicked on and then redirect them to that link and create a cookie for it so the next time the user comes they automatically get redirected.
Can anyone please tell me what am I doing wrong. I want multiple links and clicking on each link should create a cookie and redirect the user.
Can anyone provide a working jsFiddle please.
The code is below please help:
//Html
something site
something2 site
// Javascript
function redirectOne(state)
{
createCookie('state', state, 90);
window.location.href = "www.something1.com" + state;
}
function redirectTwo(state)
{
createCookie('state', state, 90);
window.location.href = "www.something2.com" + state;
}
var cookie = readCookie('state');
if (cookie != null)
{
window.location.href = "www.something.com" + cookie;
}
function createCookie(name,value,days) {
if (days)
{
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = "; expires="+date.toGMTString();
}
else var expires = "";
document.cookie = name+"="+value+expires+"; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
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,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function eraseCookie(name) {
createCookie(name,"",-1);
}

Your problem is that when you call this line in each function
createCookie('state', state, 90);
It's taking the value of '/home' from the onClick event and passing it to the cookie creation routine. You should be passing in something other than '/home' for both functions.
something site
something2 site
// Javascript
function redirectOne(state)
{
createCookie('state', state, 90);
window.location.href = state+'/home';
}
You do not need the redirectTwo function at all.

Cookie value to define style on page load

I am using the scripts from here http://www.quirksmode.org/js/cookies.html and have successfully created a cookie.. it is set based on the users response to the age drop down. However I am having trouble doing anything with it. I would like to have a style defined if a cookie is present. Here is the bulk of my scripts..
function createCookie(name,value,days){
if (days) {
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = "; expires="+date.toGMTString();
}
else var expires = "";
document.cookie = name+"="+value+expires+"; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
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,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function checkAge(){
var min_age = 13;
var year = parseInt(document.forms["emailForm"]["year"].value);
var month = parseInt(document.forms["emailForm"]["month"].value) - 1;
var day = parseInt(document.forms["emailForm"]["day"].value);
var theirDate = new Date((year + min_age), month, day);
var today = new Date;
if ( (today.getTime() - theirDate.getTime()) < 0) {
var el = document.getElementById('emailBox');
if(el){
el.className += el.className ? ' youngOne' : 'youngOne';
}
document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>";
createCookie('age','not13',0)
return false;
}
else {
createCookie('age','over13',0)
return true;
};
};
window.onload=function(){
var x = readCookie('not13');
if (x) {
document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>";
}
}
Age verification works and cookie is set.... no errors (from Firebug).. can anyone see what I am doing wrong?

with jQuery would be something like this
if (x) {
var style = "<style type=\"text/css\">.form {display:none}</style>";
$("header").append(style);
}

Looking at your code it should work. There's nothing incorrect about it.
The only thing I would suggest is that instead of injecting a style tag into a empty div, inject a link tag into the head. This will mean that your css changes and maintainance won't need to touch the js code.

I got it.. I was looking for the cookie value and needed to look for the name and then create an if statement based on the value. so..
var x = readCookie('age');
if (x=='not13') {
document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>";
}