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localstorage of a classlist

soo, i am trying to use localstorage to store the classlist so it will remember whether or not something was added to their favorites list. i need to do this with JavaScript. The error provided comes from the console in my web browser (chrome)
The ERROR
main.js:99 Uncaught TypeError: Cannot read property 'value' of undefined
at storeFavo (main.js:99)
at HTMLButtonElement.favorites (main.js:71)
HTML
<!-- Showcase -->
<section class="showcase">
<div class="container grid ">
<div class="showcase-form card">
<h2>*Input Car Name*</h2>
<img alt="" src="#" >
<button id="favo" class="btn">Add to Favorites</button>
<button id="info" class="btn">More Info</button>
</div>
</div>
</section>
JavaScript
window.addEventListener('load', init);
const info = document.querySelector('#info');
const div1 = document.querySelector('.moreInfo');
const favo = document.querySelector('#favo');
let apiUrl = 'webservice/includes/actions.php';
let apiUrl2 = 'webservice/index.php';
let Favos = document.getElementById('favo').getElementsByClassName('favorited')[0];
function init() {
info.addEventListener('click', moreInfo);
favo.addEventListener('click', favorites);
if (typeof window.localStorage === "undefined") {
console.error('Local storage is not available in your browser');
return;
}
checkFromLocalStorage()
carList;
}
function carList() {
fetch(apiUrl)
.then((response) => {
if (!response.ok) {
throw new Error(response.statusText);
}
return response.json();
})
.then(getAjaxSuccessHandler)
.catch(getAjaxErrorHandler);
}
function getAjaxSuccessHandler(data) {
console.log(data);
}
function getAjaxErrorHandler(data) {
console.error(data);
}
// Generate Cards
// getCars.map((item)=>{
// return (
// <div>
// <p> {item.brand}</p>
// <p> {item.type}</p>
// </div>
// );
// }),
// More Info Button
function moreInfo() {
let title= document.createElement('h1');
title.innerHTML = 'Info';
div1.appendChild(title)
console.log("info?")
if (div1.style.display == 'block'){
div1.style.display = 'none';
} else {
div1.style.display = 'block';
}
}
// Add To Favorites Button
function favorites() {
console.log("favo")
if (favo.classList == 'btn') {
favo.classList.remove('btn')
favo.classList.add('favorited')
favo.innerHTML = 'Remove from favorites';
storeFavo()
}
else {
favo.classList.remove('favorited')
favo.classList.add('btn')
favo.innerHTML = 'Add to Favorites';
deleteClickHandler()
}
}
//Check
/**
* Is local storage is available on page load? Let's fill the form
*/
function checkFromLocalStorage() {
if (localStorage.getItem('favos') !== null) {
Favos.value = localStorage.getItem('favos');
}
}
//Store
/**
* After submitting the form, let's save the values in the local storage
*
* #param e
*/
function storeFavo(e) {
localStorage.setItem('favos', Favos.value);
localStorage['Favos'] = document.getElementById("favo")
}
//Delete
/**
* Make sure we clean up the local storage again
*
* #param e
*/
function deleteClickHandler(e) {
localStorage.removeItem('favos');
}
CSS
.favorited {
display: inline-block;
padding: 10px 30px;
cursor: pointer;
background: #470aed;
color: #ffffff;
border: none;
border-radius: 5px;
}
.btn {
display: inline-block;
padding: 10px 30px;
cursor: pointer;
background: var(--primary-color);
color: #ffffff;
border: none;
border-radius: 5px;
}
I will do my very best to respond fast and to provide any needed information if asked for.

Check the documentation of localStorage.setItem https://developer.mozilla.org/en-US/docs/Web/API/Storage/setItem, you can write only string values, but you are trying to write an Object value (https://developer.mozilla.org/en-US/docs/Web/API/Document/getElementsByClassName). If you want to have some persistence fo your HTML element, you can save outerHTML https://developer.mozilla.org/ru/docs/Web/API/Element/outerHTML to the storage and parse it on load.

single intersection observer for multiple entries

cannot fully understand the IntersectionObserver
in the example below, everything works fine, but I'm trying to write only one single observer for multiple entries
and I'm getting various error messages.
Pls, help
let io = new IntersectionObserver((entries)=>{
entries.forEach(entry=>{
if(entry.isIntersecting){navt.classList.remove('navt1');}
else{navt.classList.add('navt1');}
})
})
let io2 = new IntersectionObserver((entries)=>{
entries.forEach(entry=>{
if(entry.isIntersecting){gotopw.style.display = 'block';}
else{gotopw.style.display = 'none';}
})
})
$(document).ready(function(){
io.observe(document.querySelector('#wrapt'));
io2.observe(document.querySelector('#apanel'));
});

Every intersecting entity refers to the element that is intersecting. So to create a single IntersectionObserver you simply have to take advantage of that.
This is a simplified example to show the concept. Note there are two "boxes" that can scroll into view. As they scroll into view the background color changes individually. I used an intersection ratio so you can see the change happen.
The modify() and revert() functions represent operations you would perform in one of the two intersection thresholds.
The test for the element id is the trick that allows the use of one IntersectionObserver for multiple elements.
Scroll slowly to see both boxes.
let io = new IntersectionObserver((entries) => {
entries.forEach(entry => {
if (entry.isIntersecting && entry.intersectionRatio > 0.5) {
modify(entry.target);
} else {
revert(entry.target);
}
})
}, {
threshold: 0.5
})
function modify(el) {
if (el.id === "wrapt") {
el.style.backgroundColor = 'red';
}
if (el.id === "apanel") {
el.style.backgroundColor = 'green';
}
}
function revert(el) {
if (el.id === "wrapt") {
el.style.backgroundColor = 'initial';
}
if (el.id === "apanel") {
el.style.backgroundColor = 'initial';
}
}
io.observe(document.querySelector('#wrapt'));
io.observe(document.querySelector('#apanel'));
#wrapt {
border: 2px solid black;
height: 100px;
width: 100px;
}
#apanel {
border: 2px solid blue;
height: 100px;
width: 100px;
}
.empty {
height: 400px;
width: 100px;
}
<div class="empty"> </div>
<div id="wrapt">Wrapt</div>
<div class="empty"></div>
<div id="apanel">aPanel</div>

Change button color based on screen size

What I am trying to achieve is when my device size is less than 736 px, the button should animate. I got the button working correctly, however, I’m struggling to work with the specific screen size.
$(window).resize(function() {
if ($(window).width() <= 736) {
// do something
let myBtn = document.querySelector(".btn");
let btnStatus = false;
myBtn.style.background = "#FF7F00";
function bgChange() {
if (btnStatus == false) {
myBtn.style.background = "#FF0000";
btnStatus = true;
}
else if (btnStatus == true) {
myBtn.style.background = "#FF7F00";
btnStatus = false;
}
}
myBtn.onclick = bgChange;
}
});
.btn {
width: 200px;
height: 100px;
text-align: center;
padding: 40px;
text-decoration: none;
font-size: 20px;
letter-spacing: .6px;
border-radius: 5px;
border: none;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<button class="btn">CLICK ME</button>

Here's an implementation of what you're trying to do that uses:
class to alter button styling instead of style,
vanilla JavaScript instead of jQuery.
Using class is a good idea, as it keeps the styling in the CSS and out of the JavaScript code.
Using vanilla JavaScript whenever you can is preferable.
Here are the two new classes:
.btn-small-screen {
background: #FF7F00;
}
.btn-clicked {
background: #FF0000;
}
.btn-small-screen class is applied when the window is small, .btn-clicked is toggled whenever the button is clicked.
Here's the JavaScript code:
let myBtn = document.querySelector('.btn');
let isSmallWindow = () => window.innerWidth <= 736;
function toggleButtonOnClick () {
myBtn.classList.toggle('btn-clicked');
}
function setButtonMode () {
if (isSmallWindow()) {
myBtn.classList.add('btn-small-screen');
myBtn.addEventListener('click', toggleButtonOnClick);
} else {
myBtn.classList.remove('btn-small-screen');
myBtn.classList.remove('btn-clicked');
myBtn.removeEventListener('click', toggleButtonOnClick);
}
}
// setup mode on resize
window.addEventListener('resize', setButtonMode);
// setup mode at load
window.addEventListener('load', setButtonMode);
References:
Document.querySelector()
Window.innerWidth
Element.classList
DOMTokenList.toggle()
DOMTokenList.add()
DOMTokenList.remove()
EventTarget.addEventListener()
A working example:
let myBtn = document.querySelector('.btn');
let isSmallWindow = () => window.innerWidth <= 736;
function toggleButtonOnClick () {
myBtn.classList.toggle('btn-clicked');
}
function setButtonMode () {
if (isSmallWindow()) {
myBtn.classList.add('btn-small-screen');
myBtn.addEventListener('click', toggleButtonOnClick);
} else {
myBtn.classList.remove('btn-small-screen');
myBtn.classList.remove('btn-clicked');
myBtn.removeEventListener('click', toggleButtonOnClick);
}
}
// setup small mode on resize
window.addEventListener('resize', setButtonMode);
// setup small mode at load
window.addEventListener('load', setButtonMode);
.btn {
width: 200px;
height: 100px;
text-align: center;
padding: 40px;
text-decoration: none;
font-size: 20px;
letter-spacing: .6px;
border-radius: 5px;
border: none;
}
.btn-small-screen {
background: #FF7F00;
}
.btn-clicked {
background: #FF0000;
}
<button class="btn">CLICK ME</button>
Note: There is one optimization that I left out, so the code would be easier to follow.
Notice that setButtonMode() changes the DOM every time, even though it might already be set to the desired mode. This is inefficient.
To improve efficiency and only change the DOM when necessary, you could introduce a state variable (call it smallMode), and set it true whenever appropriate. Like so:
let smallMode = false;
function setButtonMode () {
if (isSmallWindow()) {
if (!smallMode) {
myBtn.classList.add('btn-small-screen');
myBtn.addEventListener('click', toggleButtonOnClick);
smallMode = true;
}
} else if (smallMode) {
myBtn.classList.remove('btn-small-screen');
myBtn.classList.remove('btn-clicked');
myBtn.removeEventListener('click', toggleButtonOnClick);
smallMode = false;
}
}

JS & HTML - place on html on which the JS script will appear

I'm quite new to JS.
I want to have my html page stay the same when JS text will be appearing in one exact place without starting from blank page.
I trigger JS function via button on HTML, function in HTML:
function match () {
setTimeout(function () {
player_hp -= monster_dmg
monster_hp -= player_dmg
if (player_hp<=0) {
document.write("\nPlayer dies!")
menu();
return;
}
if (monster_hp<=0) {
document.write("\nPlayer wins!")
menu();
return;
}
if (fight=1) {
document.write("\nPlayer hp:" + player_hp)
document.write("\nMonster hp:" + monster_hp)
document.write("\n");
match()
}
}, interval)
}

One easy way to handle this is to simply create a <div> or a <span> element that has an ID attribute like this:
<div id="status"> </div>
Now you can access this element by using the Javascript method
document.querySelector("#status") and then use the innerHTML function of that element to change the internal content. You can even place the document.querySelector function into a convenient function which I have named send_status()
Here's the whole thing
/* default values */
var player_hp = 300;
var monster_dmg = 30;
var monster_hp = 200;
var interval = 500;
var player_dmg = 50;
match();
/* heres a function that will replace your document.write() functions */
function send_status(message) {
document.querySelector("#status").innerHTML = message;
}
function match() {
setTimeout(function() {
player_hp -= monster_dmg
monster_hp -= player_dmg
if (player_hp <= 0) {
send_status("\nPlayer dies!") // replaced document.write with send_status
menu();
return;
}
if (monster_hp <= 0) {
send_status("\nPlayer wins!")
menu();
return;
}
if (fight = 1) {
send_status("\nPlayer hp:" + player_hp)
send_status("\nMonster hp:" + monster_hp)
send_status("\n");
match()
}
}, interval)
}
function menu() {}
#game {
width: 100%;
height: 100px;
border: 2px solid black;
}
#status {
width: 100%;
height: 50px;
background-color: grey;
}
<div id="game">Game Goes Here</div>
<!-- here is your status area -->
<div id="status"></div>

You should create a results div, in which will be shown the match result.
Just add <div id="match_results"></div> in your HTML code.
And replace all yours document.write() for
document.getElementById('match_results').innerHTML += "<br>Player wins!"
This command is appending content in the element with ID match_results.
You should use <br> instead of \n because it is the proper way to break line in HTML code.

Javascript Less Sorter

Problem:
I want to make a Less-sorting script for myself. When i enter Less Code in the textarea and click the button, p#result should output the sorted Less Code.
The Less Code should be sorted like this:
{
Mixins(They all start with ".mx")
Properties(Sorted in alphabetic Order)
}
Here is what i have got so far:
index.html:
<head>
<script src="jquery.min.js"></script>
</head>
<textarea id="input" style="width: 600px; height: 300px; resize: none;">
</textarea>
<p id="result" style="max-width: 600px; word-wrap: break-word;"></p>
<button>Sort</button>
<script src="jquery.sorter.js"></script>
jquery.sorter.js:
var result = "",
mixins = "",
properties = "";
$("button").on("click", function () {
var textarea = $('#input').val().split('\n');
function checkLine(position) {
var index;
for (index = position; index < textarea.length; ++index) {
var line = textarea[index].trim();
if (line.includes("{") === true)
{
result = result + mixins + "<br>" + properties + line + "<br>";
mixins = "";
properties = "";
checkLine(index + 1);
} else if (line.includes("}") === true)
{
result = result + mixins + properties + line + "<br>";
mixins = "";
properties = "";
break;
} else if (line.includes(".mx") === true)
{
mixins = mixins + line + "<br>";
} else if (line.includes(":") === true)
{
properties = properties + line + "<br>";
} else
{
result = result + "<br>";
}
console.log(index + ": " + mixins + " " + properties);
}
}
checkLine(0);
$("p#result").append(result);
$("button").hide();
});
If i enter this:
.frame {
color: blue;
background-color: white;
.mx-hello(white);
.framesecond {
font-size: 12px;
background: green;
.mx-test(white);
}
}
I should get al least this output: (I didnt think of a sorting mechanism yet... :D)
.frame {
.mx-hello(white);
color: blue;
background-color: white;
.framesecond {
.mx-test(white);
font-size: 12px;
background: green;
}
}
But i get this Output:
.frame {
.mx-hello(white);
color: blue;
background-color: white;
.framesecond {
.mx-test(white);
font-size: 12px;
background: green;
}
.mx-test(white);
font-size: 12px;
background: green;
}
.mx-hello(white);
color: blue;
background-color: white;
.framesecond {
.mx-test(white);
font-size: 12px;
background: green;
}
.mx-test(white);
font-size: 12px;
background: green;
}
Background - Story:
I work for a Web-Development Company. My Less Code always looks a bit messy, but we have guidelines how to format our Code. If im done with a Project i always sit there hour for hour just rearranging Less Code. Then i thought to myself: "There must be an easier solution for my problem!". So i googled and googled and nothing really worked. Then i decided to try it myself and thats why i am here!
I hope you understand my Problem, if something is unclear please let me know so i can edit my Question! (Im not so good at javascript, so any help is appreciated! :D)

I took a look at it to see if I could solve this one. Check this out:
Codepen: https://codepen.io/huppys/pen/VrbxLd?editors=1010
I replaced the string.includes("something") with some regular expressions to be able to filter even for some different kind of less expressions.
Plus: Properties get sorted. After finding a property the string describing the property gets pushed into an array. Before adding the found properties to the output string they get sorted.
Side note: What IDE or editor are you using for writing your LESS code? Probably it could take care of the syntax sorting itself?