Develop Reference

make javascript function saved

Im using a javascript function to change color on some icons with dataset.
i cant find out how i can make the color that i change with a click, to stay that way.
this is the javascript function:
window.onload = oppdater;
function oppdater() {
const clickHandler = function () {
this.style.color =
this.style.color != this.dataset.activeColor ?
this.dataset.activeColor :
this.dataset.disabledColor;
};
for (const element of document.querySelectorAll(".active-color-aware")) {
element.onclick = clickHandler;
}
}
<div>
<img src="img/mug_test.png" height="200px" width="200px">
<p>fillifjonka grå</p>
<div id="icon_colors" class="center_icon_text">
<i data-active-color="green" data-disabled-color="#6080a0" class="fas fa-home fa-3x active-color-aware"></i>
<i data-active-color="yellow" data-disabled-color="#6080a0" class="fas fa-grin-hearts fa-3x active-color-aware"></i>
<i data-active-color="red" data-disabled-color="#6080a0" class="fas fa-heart-broken fa-3x active-color-aware"></i>
</div>
</div>

If you want to save the info event after user closes the browser, you can leverage the localstorage
// Save
localStorage.setItem("activeColor", "red");
// Get
var activeColor = localStorage.getItem("activeColor");

How to target all elements with Jquery on click

Only first element getting clicked not all, how to get alert on all elements.
Jsfiddle
var btn = document.querySelector(".box i");
btn.onclick = function () {
alert('hello');
}
<div class="box">
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
</div>

Try querySelectorAll for select all then attract onclick to all element
var btnlist = document.querySelectorAll(".box i");
btnlist.forEach(element =>{element.onclick = function () {
alert('hello');
}});
<link href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" integrity="sha384-wvfXpqpZZVQGK6TAh5PVlGOfQNHSoD2xbE+QkPxCAFlNEevoEH3Sl0sibVcOQVnN" crossorigin="anonymous">
<div class="box">
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
<i class="fa fa-address-book-o" aria-hidden="true"></i>
</div>

Despite the title of the question, you don't currently use jQuery in your code. So, I provide 2 solutions:
jQuery:
jQuery('.box i').click(function() {
alert('hello');
});
Pure JS
window.addEventListener('click', function(e) {
// or e.target.classList.contains('fa-address-book-o')
if (e.target.className === 'fa fa-address-book-o') { // Better to add some additional class to identify element, like "fireAlert" for instance.
alert('hello');
}
});
Alternatively, you could select icons with query selector and add individual event listeners to all of them in a loop, but it's bad for performance & generally not considered a good thing to do.

The reason why it only work on the first element is that using .querySelector() method will select only the first element the meet your selector criteria, to be able to select all the elements you have to use .querySelectorAll() which will return a NodeList which can iterate through like this:
var btns = document.querySelectorAll(".box i");
btns.forEach((el, i) => {
el.onclick = function () {
console.log(`Hello! ${i}`);
}
});
<div class="box">
<i class="fa fa-address-book-o" aria-hidden="true">1</i>
<i class="fa fa-address-book-o" aria-hidden="true">2</i>
<i class="fa fa-address-book-o" aria-hidden="true">4</i>
<i class="fa fa-address-book-o" aria-hidden="true">5</i>
</div>

how to toggle between icons when a button is clicked?

I want to switch between a moon and a sun when the dark mode is enabled or disabled.
Now I have it that I can change once, but after that it stays as a moon.
How do I fix this this?
function darkmode() {
document.body.classList.toggle('dark-mode');
document.getElementById('toggleknop').innerHTML = '<i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>';
}
<button onclick="darkmode()" id="Knop">
<span id="toggleknop"><i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i></span>
</button>

You can change/toggle easily Drak <=> Light only using CSS.
just use 'document.body.classList.toggle('dark-mode');' code only for toggle. show icon depend on the parent class. please see the snippet here:
function darkmode() {
document.body.classList.toggle('dark-mode');
}
.dark-mode button {
background: black;
color: white;
}
.dark-mode .sun-icon,
.moon-icon {
display: none;
}
.dark-mode .moon-icon {
display: inline;
}
<button onclick="darkmode()" id="Knop">
click
<span class="sun-icon">
sun <i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i>
</span>
<span class="moon-icon">
moon <i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>
</span>
</button>
Maybe it helps to solve your problem.
Thank you

var currentTheme = 'dark';
function changeTheme() {
document.body.classList.toggle('dark-mode');
if (currentTheme === 'dark') {
document.getElementById('toggleknop').innerHTML = '<i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i>';
currentTheme = 'sun';
}else {
document.getElementById('toggleknop').innerHTML = '<i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>';
currentTheme = 'dark';
}
}

You need to remember whether you are in dark mode with a variable stored outside the function:
var inDarkMode = false;
function toggleDarkMode() {
if (inDarkMode) {
document.body.classList.remove('dark-mode');
document.getElementById('toggleknop').innerHTML =
'<i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>';
inDarkMode = false;
} else {
document.body.classList.add('dark-mode');
document.getElementById('toggleknop').innerHTML =
'<i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i>';
inDarkMode = true;
}
}

Use hasClass to check if it contains class.
function darkmode() {
document.body.classList.toggle('dark-mode');
var toggleknop= document.getElementById('toggleknop');
if(toggleknop.hasClass('fa-sun')
{
toggleknop.classList.remove('fa-sun');
toggleknop.classList.add('fa-moon');
//Your styling
}
else if(toggleknop.hasClass('fa-moon') {
toggleknop.classList.remove('fa-moon');
toggleknop.classList.add('fa-sun');//Your styling
}

function darkmode() {
document.body.classList.toggle('dark-mode');
document.getElementById('toggleknop').innerHTML = document.body.classList.contains('dark-mode') ? '<i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>' : '<i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i>';
}
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/all.min.css" rel="stylesheet"/>
<button onclick="darkmode()" id="Knop">
<span id="toggleknop"><i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i></span>
</button>
function darkmode() {
document.body.classList.toggle('dark-mode');
document.getElementById('toggleknop').innerHTML = document.body.classList.contains('dark-mode') ? '<i class="fas fa-moon fa-2x" id="maan" style="color:#737eac;"></i>' : '<i class="fas fa-sun fa-2x" id="zon" style="color:#d8c658;"></i>';
}

How can I get two different events with "querySelectorAll" for each element?

I have a probleme with my code. Now if I click the first element, all elements will become red, if I click second time they will become green. I would like have two independent events for each element with class fa-heart. I will explain better: If I click the first time the first element DOM, only this element will become red, and if I click it second time, it will become green, and so for all the others. I apologize if my request is not clear. Thank you so much for your help.
<script src="https://kit.fontawesome.com/a1d70a0cda.js"></script>
<a onclick="change()"><i class="fas fa-heart"></i></a>
<a onclick="change()"><i class="fas fa-heart"></i></a>
<a onclick="change()"><i class="fas fa-heart"></i></a>
<script>
function change(){
var a = document.querySelectorAll('.fa-heart');
var qty = a.length;
var i = 0;
for(i; i<qty; i++){
if(a[i].style.color !== 'red'){
a[i].style.color = 'red';
}else{
a[i].style.color='green';
}
}
}
</script>

Add an individual listener to each <i> instead, and in the listener, check the current .style of the clicked element to figure out what to assign next:
document.querySelectorAll('.fa-heart').forEach((i) => {
i.addEventListener('click', () => {
i.style.color = i.style.color !== 'red'
? 'red'
: 'green';
});
});
<script src="https://kit.fontawesome.com/a1d70a0cda.js"></script>
<a><i class="fas fa-heart"></i></a>
<a><i class="fas fa-heart"></i></a>
<a><i class="fas fa-heart"></i></a>
Or, with event delegation:
document.addEventListener('click', (e) => {
if (!e.target.matches('.fa-heart')) {
return;
}
e.target.style.color = e.target.style.color !== 'red'
? 'red'
: 'green';
});
console.log('start');
setTimeout(() => {
console.log('adding dynamic elements');
document.body.innerHTML += `<a><i class="fas fa-heart"></i></a>
<a><i class="fas fa-heart"></i></a>
<a><i class="fas fa-heart"></i></a>`;
}, 1000);
<script src="https://kit.fontawesome.com/a1d70a0cda.js"></script>
If you must use inline handlers (which you shouldn't), pass the this (the clicked element) to the listener:
function change(i) {
i.style.color = i.style.color !== 'red'
? 'red'
: 'green';
}
<script src="https://kit.fontawesome.com/a1d70a0cda.js"></script>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>

Here you go. This will change the clicked one to green and others to red.
function change(clicked) {
document.querySelectorAll('a').forEach(el => el.setAttribute("style", "color:red"));
clicked.style.cssText ="color:green;";
}
<script src="https://kit.fontawesome.com/a1d70a0cda.js"></script>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>
<a onclick="change(this)"><i class="fas fa-heart"></i></a>

color icons upto the hover position

I have 10 circles (Fontawesome icons) horizontally placed. I want to fill colors to them when the user hover on any icon. For ex: if the user hovers on the 5th circle, all the circles upto the 5th circle should fill in color. (Something like in a rating system) How can i do it?
Following is the code which i render 10 circles.
export const RatePersonalityCard = ({}) => {
for (let score = 1; score < 11; score++) {
let scoreList = [];
scoreList.push(
<div className="trait_vote_single tooltip" style={{fontSize:'40px',color:'gray'}} onClick={() => handleClick(score)}>
{/*<div className="trait_vote_circle"></div>*/}
<i className="fa fa-circle-thin" aria-hidden="true"></i>
<a className="trait_value" style={{marginTop:'-34px',marginLeft:'-1px'}}>{score}</a>
<span className="tooltiptext2 unchange_div" style={{marginLeft: '-40px'}}>{starvalue}</span>
</div>
)
}
return (
<div className="">
<div className="single_trait_rate width_100 text_align_center">{userTraits.trait_name}</div>
<div className="trait_vote_div">
{scoreList}
</div>
</div>
);
};

You could create a hover event for each for every score list item that adds a class to the currently hovered item and everything prior. Then add a blur event to every item to remove the class.
function handleHover(e) {
let index = scoreList.indexOf(e.target);
for (let i = 0; i <= index; i++) {
scoreList[index].classList.add('highlight');
}
}
function handleBlur(e) {
scoreList.forEach(function(item) {
item.classList.remove('highlight');
});
}

No CSS example. I don't see great value in adding any JS to something that can simply done via CSS. If you also need a click event, it's as simple as 1 class on 1 span. I'd also recommend reading:
Decoupling Your HTML, CSS, and JavaScrip which my code does not do.
span .fa-star{
display: none;
}
span:hover > .fa-star{
color: yellow;
display: inline-block;
color: red;
}
span:hover > .fa-star-o{
display: none;
}
span { cursor: pointer }
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
<span>
<i class="fa fa-star-o" aria-hidden="true"></i>
<i class="fa fa-star" aria-hidden="true"></i>
<span>
<i class="fa fa-star-o" aria-hidden="true"></i>
<i class="fa fa-star" aria-hidden="true"></i>
<span>
<i class="fa fa-star-o" aria-hidden="true"></i>
<i class="fa fa-star" aria-hidden="true"></i>
<span>
<i class="fa fa-star-o" aria-hidden="true"></i>
<i class="fa fa-star" aria-hidden="true"></i>
<span>
<i class="fa fa-star-o" aria-hidden="true"></i>
<i class="fa fa-star" aria-hidden="true"></i>
</span>
</span>
</span>
</span>
</span>