We Keep Coding

Using vanilla JavaScript, is it possible to add a DOM element and fade in using CSS transition, without using setTimeout or CSS animation?

Is it possible to add an element to the page, but have it fade it, without using setTimeout()?
I am thinking that for CSS transition, it has to first have a value (opacity 0), and then, let it have another value (opacity 1), so that the transition can occur, so a setTimeout() is needed.
The snippet below can add the new row, but is it possible to make it fade in, again, not using jQuery's fadeIn(), setTimeout(), or CSS animation? Is it possible to do it using CSS transition delay?
const tableElement = document.querySelector("#tbl");
document.querySelector("#btn").addEventListener("click", ev => {
tableElement.innerHTML = `${tableElement.innerHTML}<tr><td>Hi There ${Math.random()}</td></tr>`;
});
tr {
transition: all 1s
}
tr {
opacity: 0.2
}
<button id="btn">Click</button>
<table id="tbl"></table>

fadeIn without setTimeout and css animation ;)
const tableElement = document.querySelector('#tbl');
const btn = document.querySelector('#btn');
btn.addEventListener('click', () => {
btn.setAttribute('disabled', true);
tableElement.innerHTML = `${tableElement.innerHTML}<tr><td class='hidden'>Hi There ${Math.random()}</td></tr>`;
const el = document.querySelector('.hidden');
el.classList.remove('hidden');
fadeIn(el);
});
function fadeIn(el, display) {
el.style.opacity = 0;
el.style.display = display || 'block';
(function fade() {
let val = parseFloat(el.style.opacity);
let proceed = !(((val += 0.04) > 1));
if (parseInt(el.style.opacity) === 1) {
btn.removeAttribute('disabled');
}
if (proceed) {
el.style.opacity = val;
requestAnimationFrame(fade);
}
})();
}
.hidden {
display: none;
}
<button id="btn">Click</button>
<table id="tbl"></table>

How could I make this active onclick?

var span = document.getElementById('loading_dots');
var int = setInterval(function() {
if ((span.innerHTML += '●').length == 4)
span.innerHTML = '';
}, 400);
(function(){
var loading_dots = document.getElementById("loading_dots"),
show = function(){
loading_dots.style.display = "block";
setTimeout(hide, 5000); // 5 seconds
},
hide = function(){
loading_dots.style.display = "none";
};
show();
})();
How can I make it so loading_dots start on the click of a button, and re-activates everytime I click the button? the bottom function is to stop it after 5 seconds, maybe could merge it into one function?
Needs to work for 3 seperate buttons and relaunch on click of each, also needs to display inside of <span class="loading_dots" id="loading_dots"></span> any method is fine, css, jquery, or javascript

here is a jQuery version:
(function ( $ ) {
$.fn.loader = function( options ) {
var settings = $.extend({
text:"●",
spn: undefined
}, options );
$.each(this, function(){
var btn = this;
var int;
var spn;
if (settings.spn === undefined) {
spn = $("<span/>" , { "class":"loading_dots" });
$(btn).append(spn);
} else {
spn= $(settings.spn);
}
var show = function(){
btn.setAttribute("disabled", "disabled")
clearInterval(int);
spn.show();
int = setInterval(function() {
if ((spn[0].innerHTML += settings.text).length == 4)
spn.html("");
}, 400);
setTimeout(hide, 5000); // 5 seconds
}
var hide = function (){
spn.hide();
btn.removeAttribute("disabled", "disabled")
clearInterval(int);
}
btn.addEventListener("click", show);
});
};
}( jQuery ));
// now bind it by its class, this only need to be run once every time new button is added to the html
$(".btn").loader({spn:".loading_dots"});
// and you could also specify the text by
// $(".btn").loader({text: "*"});
.loading_dots {
color:red;
display:none;
width:100%;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div>
<span class="loading_dots"></span>
<button class="btn" type="button" >
submit
</button>
<button class="btn" type="button" >
submit
</button>
</div>

If you want to add an event listener for a button click, just select the buttons, and add the listeners in a loop:
document.querySelectorAll("button").forEach(e => e.addEventListener("click", myFunc));
Alternatively, listen for any click, then check if the event's target is a button:
document.addEventListener("click", (e) => if (e.target.tagName == "BUTTON") myFunc());

You could use CSS for the most part of your code, and than simply toggle a show class on the parent #loading element:
const Loading = () => {
let tOut = null;
const el = document.querySelector("#loading");
const show = () => {
el.classList.add('show');
tOut = setTimeout(hide, 5000);
};
const hide = () => {
el.classList.remove('show');
clearTimeout(tOut);
};
return {
show,
hide
};
};
const loadingDots = Loading();
const loadBtns = document.querySelectorAll('.load');
[...loadBtns].forEach(el => el.addEventListener('click', loadingDots.show));
// you can always use loadingDots.hide() to hide when needed (before the 5sec ticks out)
#loading {
position: fixed;
z-index: 100;
top:0;
left: 0;
width:100vw;
height:100vh;
display:flex;
background: rgba(0,0,0,0.5);
color: #fff;
font-size: 3em;
align-items: center;
justify-content:center;
visibility: hidden;
opacity: 0;
transition: 0.4s;
}
#loading.show {
opacity: 1;
visibility: visible;
}
#keyframes blink {
50% {opacity: 1;}
}
#loading i:after {content: "\25cf";}
#loading i { opacity: 0; animation: blink 1.2s infinite; }
#loading i:nth-child(2) { animation-delay: .2s; }
#loading i:nth-child(3) { animation-delay: .4s; }
<div id="loading"><i></i><i></i><i></i></div>
<button class="load">LOAD</button>
<button class="load">LOAD</button>
<button class="load">LOAD</button>

A plain javascript version with the option to programmatically/manually stop displaying the loading dots. Just pass the id of the parent element you want the loading to be attached to. By default the loading will be appended to the parent but you can optionally pass an object as the last parameter with a position property.
function removeLoading(id) {
var parent = document.getElementById(id);
var spans = parent.getElementsByClassName("loading_dots");
while (spans.length > 0) {
var span = spans[0];
if (span.dataset.timerId) {
clearTimeout(span.dataset.timerId);
}
span.remove();
}
}
function addLoading(id, options) {
options = options || {};
var parent = document.getElementById(id);
var existingSpans = parent.getElementsByClassName("loading_dots");
if (existingSpans.length > 0) {
removeLoading(id);
}
var span = document.createElement("span");
span.setAttribute("class", "loading_dots");
if (options.timerId) {
span.dataset.timerId = options.timerId;
}
parent.insertAdjacentElement(options.position || "beforeend", span);
setInterval(function () {
if ((span.innerHTML += '●').length == 4)
span.innerHTML = '';
}, 400)
}
function addLoadingWithTimeout(id, ms, options) {
options = options || {};
var timerId = setTimeout(function () { removeLoading(id) }, ms);
options.timerId = timerId;
addLoading(id, options);
}
<p id="load1">Load 1 - Will stop automatically in 3 seconds after starting. </p>
<button onclick="addLoadingWithTimeout('load1', 3000)">Start Load 1</button>
<button onclick="removeLoading('load1')">Stop Load 1</button>
<p id="load2">Load 2 - Only manual Stop </p>
<button onclick="addLoading('load2')">Start Load 2</button>
<button onclick="removeLoading('load2')">Stop Load 2</button>

Here you go. on the HTML side, you just pass the event to the button that you want and then the id, as a string, of the span/div where you want the load icons to appear.
HTML:
<button id="btn" onclick="load(event, 'loadDiv')">Load</button>
<div>
<span id="loadDiv"></span>
</div>
Below, we are getting the btn id from event so you don't have to manually pass it everytime. Then we are defining function for the innerhtml icons. Lastly, we are running the showIcon function every .4s and then clearing the interval after 5 seconds.
JS:
function load(e, location) {
var btn = document.getElementById(e.srcElement.id)
var loadDiv = document.getElementById(location)
function showLoad() {
if (loadDiv.innerHTML.length < 3) {
return loadDiv.innerHTML += '●'
}
loadDiv.innerHTML = ''
}
(function() {
var loadIcons = setInterval(function() {
showLoad()
}, 400)
var clear = setTimeout(function() {
clearInterval(loadIcons)
}, 5000)
})()
}
Hope this helps!

You can define your code in a function and add click handler to the button.
function myFunc() {
var span = document.getElementById('loading_dots');
var int = setInterval(function() {
if ((span.innerHTML += '●').length == 4)
span.innerHTML = '';
}, 400);
(function(){
var loading_dots = document.getElementById("loading_dots"),
show = function(){
loading_dots.style.display = "block";
setTimeout(hide, 5000); // 5 seconds
},
hide = function(){
loading_dots.style.display = "none";
};
show();
})();
}
document.getElementById("myBtn1").addEventListener("click", myFunc);
document.getElementById("myBtn2").addEventListener("click", myFunc);

Reverse background-position animation without resetting

I created an animation with CSS that changes the background-position of an element over time, to create a sort of scrolling effect with the background.
#keyframes stars-animate {
0% {
background-position: 0 -500px;
}
100% {
background-position: 2000px -500px;
}
}
This works perfectly. However, I also want to start to rewind the animation and create a reverse scrolling event. This is triggered by some irrelevant action.
function triggerReverse(element) {
element.style.animationDirection = 'reverse';
}
However, when I set the animation-direction to reverse, it does work, but not before it flips the entire background.
Am I doing it wrong, or is that the wrong way to do it, and if so, what is the right way?
Edit: I need to be able to reverse the animation while it is playing

UPDATE
The renewed sample code below provide the effect that enables a user to interrupt/pause the animation (during the first iteration) and immediately start to reverse the animation.
Here it is using time to control. Record the elapsed time from the beginning of animation, and calculate how to start the reverse animation. There are 2 iterations defined in css to make a whole loop. Without user intervention, the animation pauses/stops after the first iteration. But if there is, pause the iteration and immediately re-start it with a calculated animation-delay time. This will looks like an immediate reverse, however actually it is a new start.
There is also a trick on how to re-start the animation. Please refer to the code comment.
I searched around but found nobody has mentioned a similar scenario so far, nor a similar solution. Instead of to use time to control, I would like to see other better approaches.
My test also proves that different running environments render slightly different smoothness. Fortunately, here in SO is the best.
Try the solution to see if it can works well in your own scenario.
const span = document.querySelector('span'),
button = document.querySelector('button'),
duration = 10; // animation-during
let startTime;
span.addEventListener('animationstart', () => {
startTime = Date.now();
button.style.visibility = 'visible';
});
span.addEventListener('animationiteration', () => span.style.animationPlayState = 'paused');
span.addEventListener('animationend', () => {
button.style.visibility = 'hidden';
});
button.addEventListener('click', () => {
span.classList.remove('my_anim');
void span.offsetWidth; // safely apply changes
span.classList.add('my_anim');
const elapsed = Date.now() - startTime;
const delay = (elapsed < duration * 1000) ? (elapsed / 1000 - duration * 2) : -duration;
span.style.animationDelay = `${delay}s`;
span.style.animationPlayState = 'running';
});
span.my_anim {
animation: 10s 2 alternate my_move;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
visibility: hidden;
}
<div>
<span class="my_anim">#</span>
</div>
<button>reverse</button>
This example does not use background-position for animation but a plain character.
const span = document.querySelector("span"),
button = document.querySelector("button");
span.addEventListener(
"animationiteration",
function() {
this.classList.add("paused");
button.style.visibility = "visible";
}
);
button.addEventListener(
"click",
function() {
this.style.visibility = "hidden";
span.classList.remove("paused");
}
);
span {
animation: 3s 2 alternate my_move;
}
span.paused {
animation-play-state: paused;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
visibility: hidden;
}
<div>
<span>#</span>
</div>
<button>reverse</button>
NB: Use -webkit- prefix for css animation when necessary.

building off of #themefield's answer above - thanks, #themefield! - this way works the 'best', not perfect. (Sometimes the letter isn't in exactly the right spot when it reverses.)
The approach that worked was
a) reset animation to forward / reverse at the end
b) replace the animation with its opposite on toggling, setting a - start time to try to position it where it was.
Often it works pretty good, sometimes a lot off.
span = document.querySelector('span')
button = document.querySelector('button')
timerElement = document.querySelector('#timerId')
duration = 3; // animation-during
let startTime = Date.now();
toSec = (msec) => msec / 1000
elapsedTimeMsec = () => Date.now() - startTime
elapsedTimeSec = () => toSec(elapsedTimeMsec())
updateTimer = () => timerElement.innerHTML = `${elapsedTimeSec().toPrecision(2)}s`
let intervalHandle;
startTimer = () => {
intervalHandle = window.setInterval(() => {
updateTimer()
}, 500)
}
endTimer = () => {
window.clearInterval(intervalHandle)
intervalHandle = null
}
span.addEventListener('animationstart', () => {
startTime = Date.now();
startTimer()
});
span.addEventListener('animationiteration', () => span.style.animationPlayState = 'paused');
toggleAnimation = (shouldDelay) => {
span.classList.remove('my_anim');
void span.offsetWidth;
span.classList.add('my_anim');
if(span.style.animationDirection !== 'reverse')
span.style.animationDirection = 'reverse';
else
span.style.animationDirection = 'normal';
if(shouldDelay !== null && shouldDelay) {
span.style.animationDelay = `-${elapsedTimeSec()}s`;
} else {
span.style.animationDelay = `0s`;
}
span.style.animationPlayState = 'running';
}
span.addEventListener('animationend', () => {
endTimer()
updateTimer()
toggleAnimation();
});
button.addEventListener('click', () => {
endTimer()
updateTimer()
toggleAnimation(true) // todo pass in delay!
});
span.my_anim {
font-size: 54px;
animation: 3s 1 normal both my_move;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
/*visibility: hidden;*/
}
#timerId {
font-size: 24px;
color: darkturquoise;
position: fixed;
bottom: 0;
left: 50%;
}
<div>
<span class="my_anim">#</span>
</div>
<button>reverse</button>
<span id="timerId"></span>

Javascript fade out animation function (no jQuery)

So I made this function and it works:
var opacity = 9;
function func() {
$("action").style.opacity = "0." + opacity;
opacity--;
if (opacity == -1) { window.clearInterval(fading); }
}
var fading = window.setInterval("func()", 200);
But thats acutally not really one single function.
So I did this:
function fadeOut(ms) {
var opacity = 9;
function func() {
$("action").style.opacity = "0." + opacity;
opacity--;
if (opacity == -1) { window.clearInterval(fading); }
}
var fading = window.setInterval("func()", ms);
}
fadeOut(200);
And suddenly func() is undefined.
Help ? :|

Change:
var fading = window.setInterval("func()", ms);
to
var fading = window.setInterval(func, ms);
Am not sure what $("action") return though, if its jQuery then style is not a valid member of $("action").

How to do fade-in and fade-out with JavaScript and CSS

I want to make an HTML div tag fade in and fade out.
I have some code that fades out, but when I fade in, the opacity of the div stays at 0.1 and doesn't increase.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
<head>
<title>Fade to Black</title>
<script type="text/javascript">
//<![CDATA[
function slidePanel(elementToSlide, slideSource)
{
var element = document.getElementById(elementToSlide);
if(element.up == null || element.up == false) {
setTimeout("fadeOut(\"" + elementToSlide + "\")", 100);
element.up = true;
slideSource.innerHTML = "Bring it down";
} else {
setTimeout("fadeIn(\"" + elementToSlide + "\")", 100);
element.up = false;
slideSource.innerHTML = "Take it up";
}
}
function fadeIn(elementToFade)
{
var element = document.getElementById(elementToFade);
element.style.opacity += 0.1;
if(element.style.opacity > 1.0) {
element.style.opacity = 1.0;
} else {
setTimeout("fadeIn(\"" + elementToFade + "\")", 100);
}
}
function fadeOut(elementToFade)
{
var element = document.getElementById(elementToFade);
element.style.opacity -= 0.1;
if(element.style.opacity < 0.0) {
element.style.opacity = 0.0;
} else {
setTimeout("fadeOut(\"" + elementToFade + "\")", 100);
}
}
//]]>
</script>
</head>
<body>
<div>
<div id="slideSource"
style="width:150px; height:20px;
text-align:center; background:green"
onclick="slidePanel('panel', this)">
Take It up
</div>
<div id="panel"
style="width:150px; height:130px;
text-align:center; background:red;
opacity:1.0;">
Contents
</div>
</div>
</body>
</html>
What am I doing wrong and what is the best way to fade in and fade out an element?

Here is a more efficient way of fading out an element:
function fade(element) {
var op = 1; // initial opacity
var timer = setInterval(function () {
if (op <= 0.1){
clearInterval(timer);
element.style.display = 'none';
}
element.style.opacity = op;
element.style.filter = 'alpha(opacity=' + op * 100 + ")";
op -= op * 0.1;
}, 50);
}
you can do the reverse for fade in
setInterval or setTimeout should not get a string as argument
google the evils of eval to know why
And here is a more efficient way of fading in an element.
function unfade(element) {
var op = 0.1; // initial opacity
element.style.display = 'block';
var timer = setInterval(function () {
if (op >= 1){
clearInterval(timer);
}
element.style.opacity = op;
element.style.filter = 'alpha(opacity=' + op * 100 + ")";
op += op * 0.1;
}, 10);
}

Here is a simplified running example of Seattle Ninja's solution.
var slideSource = document.getElementById('slideSource');
document.getElementById('handle').onclick = function () {
slideSource.classList.toggle('fade');
}
#slideSource {
opacity: 1;
transition: opacity 1s;
}
#slideSource.fade {
opacity: 0;
}
<button id="handle">Fade</button>
<div id="slideSource">Whatever you want here - images or text</div>

why do that to yourself?
jQuery:
$("#element").fadeOut();
$("#element").fadeIn();
I think that's easier.
www.jquery.com

Here's my attempt with Javascript and CSS3 animation
So the HTML:
<div id="handle">Fade</div>
<div id="slideSource">Whatever you want images or text here</div>
The CSS3 with transitions:
div#slideSource {
opacity:1;
-webkit-transition: opacity 3s;
-moz-transition: opacity 3s;
transition: opacity 3s;
}
div#slideSource.fade {
opacity:0;
}
The Javascript part. Check if the className exists, if it does then add the class and transitions.
document.getElementById('handle').onclick = function(){
if(slideSource.className){
document.getElementById('slideSource').className = '';
} else {
document.getElementById('slideSource').className = 'fade';
}
}
Just click and it will fade in and out. I would recommend using JQuery as Itai Sagi mentioned. I left out Opera and MS, so I would recommend using prefixr to add that in the css. This is my first time posting on stackoverflow but it should work fine.

Ok, I've worked it out
element.style.opacity = parseFloat(element.style.opacity) + 0.1;
Should be used instead of
element.style.opacity += 0.1;
Same with
element.style.opacity = parseFloat(element.style.opacity) - 0.1;
Instead of
element.style.opacity -= 0.1;
Because opacity value is stored as string, not as float. I'm still not sure though why the addition has worked.

I usually use these utility functions. element is the HTML element and duration is the desired duration in milliseconds.
export const fadeIn = (element, duration) => {
(function increment(value = 0) {
element.style.opacity = String(value);
if (element.style.opacity !== '1') {
setTimeout(() => {
increment(value + 0.1);
}, duration / 10);
}
})();
};
export const fadeOut = (element, duration) => {
(function decrement() {
(element.style.opacity -= 0.1) < 0 ? element.style.display = 'none' : setTimeout(() => {
decrement();
}, duration / 10);
})();
};

Heres my code for a fade in/out toggle functions.
fadeIn: function (len) {
var obj = this.e;
obj.style.display = '';
var op = 0;
var timer = setInterval(function () {
if (op >= 1 || op >= 1.0){
console.log('done', op)
clearInterval(timer);
}
obj.style.opacity = op.toFixed(1);
op += 0.1;
console.log(obj.style.opacity);
}, len);
return this;
},
fadeOut: function (len) {
var obj = this.e;
var op = 1;
var timer = setInterval(function () {
if (op <= 0){
clearInterval(timer);
console.log('done', op)
obj.style.display = 'none';
}
obj.style.opacity = op.toFixed(1);
op -= 0.1;
console.log(obj.style.opacity)
}, len);
return this;
},
This was from a jQuery style lib i did. hope it's helpfull. link to lib on cloud9:
https://c9.io/christopherdumas/magik_wb

I like Ibu's one but, I think I have a better solution using his idea.
//Fade In.
element.style.opacity = 0;
var Op1 = 0;
var Op2 = 1;
var foo1, foo2;
foo1 = setInterval(Timer1, 20);
function Timer1()
{
element.style.opacity = Op1;
Op1 = Op1 + .01;
console.log(Op1); //Option, but I recommend it for testing purposes.
if (Op1 > 1)
{
clearInterval(foo1);
foo2 = setInterval(Timer3, 20);
}
}
This solution uses a additional equation unlike Ibu's solution, which used a multiplicative equation. The way it works is it takes a time increment (t), an opacity increment (o), and a opacity limit (l) in the equation, which is: (T = time of fade in miliseconds) [T = (l/o)*t]. the "20" represents the time increments or intervals (t), the ".01" represents the opacity increments (o), and the 1 represents the opacity limit (l). When you plug the numbers in the equation you get 2000 milliseconds (or 2 seconds). Here is the console log:
0.01
0.02
0.03
0.04
0.05
0.060000000000000005
0.07
0.08
0.09
0.09999999999999999
0.10999999999999999
0.11999999999999998
0.12999999999999998
0.13999999999999999
0.15
0.16
0.17
0.18000000000000002
0.19000000000000003
0.20000000000000004
0.21000000000000005
0.22000000000000006
0.23000000000000007
0.24000000000000007
0.25000000000000006
0.26000000000000006
0.2700000000000001
0.2800000000000001
0.2900000000000001
0.3000000000000001
0.3100000000000001
0.3200000000000001
0.3300000000000001
0.34000000000000014
0.35000000000000014
0.36000000000000015
0.37000000000000016
0.38000000000000017
0.3900000000000002
0.4000000000000002
0.4100000000000002
0.4200000000000002
0.4300000000000002
0.4400000000000002
0.45000000000000023
0.46000000000000024
0.47000000000000025
0.48000000000000026
0.49000000000000027
0.5000000000000002
0.5100000000000002
0.5200000000000002
0.5300000000000002
0.5400000000000003
0.5500000000000003
0.5600000000000003
0.5700000000000003
0.5800000000000003
0.5900000000000003
0.6000000000000003
0.6100000000000003
0.6200000000000003
0.6300000000000003
0.6400000000000003
0.6500000000000004
0.6600000000000004
0.6700000000000004
0.6800000000000004
0.6900000000000004
0.7000000000000004
0.7100000000000004
0.7200000000000004
0.7300000000000004
0.7400000000000004
0.7500000000000004
0.7600000000000005
0.7700000000000005
0.7800000000000005
0.7900000000000005
0.8000000000000005
0.8100000000000005
0.8200000000000005
0.8300000000000005
0.8400000000000005
0.8500000000000005
0.8600000000000005
0.8700000000000006
0.8800000000000006
0.8900000000000006
0.9000000000000006
0.9100000000000006
0.9200000000000006
0.9300000000000006
0.9400000000000006
0.9500000000000006
0.9600000000000006
0.9700000000000006
0.9800000000000006
0.9900000000000007
1.0000000000000007
1.0100000000000007
Notice how the opacity follows the opacity increment amount of .01 just like in the code. If you use the code Ibu made,
//I made slight edits but keeped the ESSENTIAL stuff in it.
var op = 0.01; // initial opacity
var timer = setInterval(function () {
if (op >= 1){
clearInterval(timer);
}
element.style.opacity = op;
op += op * 0.1;
}, 20);
you will get these numbers (or something similar) in you console log. Here is what I got.
0.0101
0.010201
0.01030301
0.0104060401
0.010510100501
0.010615201506009999
0.0107213535210701
0.0108285670562808
0.010936852726843608
0.011046221254112044
0.011156683466653165
0.011268250301319695
0.011380932804332892
0.01149474213237622
0.011609689553699983
0.011725786449236983
0.011843044313729352
0.011961474756866645
0.012081089504435313
0.012201900399479666
0.012323919403474463
0.012447158597509207
0.0125716301834843
0.012697346485319142
0.012824319950172334
0.012952563149674056
0.013082088781170797
0.013212909668982505
0.01334503876567233
0.013478489153329052
0.013613274044862343
0.013749406785310966
0.013886900853164076
0.014025769861695717
0.014166027560312674
0.014307687835915801
0.01445076471427496
0.01459527236141771
0.014741225085031886
0.014888637335882205
0.015037523709241028
0.015187898946333437
0.01533977793579677
0.015493175715154739
0.015648107472306286
0.01580458854702935
0.015962634432499644
0.01612226077682464
0.016283483384592887
0.016446318218438817
0.016610781400623206
0.01677688921462944
0.016944658106775732
0.01711410468784349
0.017285245734721923
0.017458098192069144
0.017632679173989835
0.01780900596572973
0.01798709602538703
0.018166966985640902
0.01834863665549731
0.018532123022052285
0.018717444252272807
0.018904618694795535
0.01909366488174349
0.019284601530560927
0.019477447545866538
0.0196722220213252
0.019868944241538455
0.02006763368395384
0.02026831002079338
0.020470993121001313
0.020675703052211326
0.02088246008273344
0.021091284683560776
0.021302197530396385
0.02151521950570035
0.021730371700757353
0.021947675417764927
0.022167152171942577
0.022388823693662
0.022612711930598623
0.022838839049904608
0.023067227440403654
0.02329789971480769
0.023530878711955767
0.023766187499075324
0.024003849374066077
0.02424388786780674
0.024486326746484807
0.024731190013949654
0.024978501914089152
0.025228286933230044
0.025480569802562344
0.025735375500587968
0.025992729255593847
0.026252656548149785
0.026515183113631283
0.026780334944767597
0.027048138294215273
0.027318619677157426
0.027591805873929
0.02786772393266829
0.028146401171994972
0.028427865183714922
0.02871214383555207
0.02899926527390759
0.029289257926646668
0.029582150505913136
0.029877972010972267
0.030176751731081992
0.030478519248392812
0.03078330444087674
0.031091137485285508
0.031402048860138365
0.03171606934873975
0.03203323004222715
0.03235356234264942
0.03267709796607591
0.03300386894573667
0.03333390763519403
0.03366724671154597
0.03400391917866143
0.03434395837044805
0.03468739795415253
0.03503427193369406
0.035384614653031
0.035738460799561306
0.03609584540755692
0.03645680386163249
0.03682137190024882
0.03718958561925131
0.03756148147544382
0.03793709629019826
0.03831646725310024
0.038699631925631243
0.03908662824488755
0.039477494527336426
0.03987226947260979
0.040270992167335894
0.04067370208900925
0.04108043910989934
0.04149124350099834
0.04190615593600832
0.042325217495368404
0.04274846967032209
0.04317595436702531
0.04360771391069556
0.044043791049802515
0.04448422896030054
0.04492907124990354
0.04537836196240258
0.045832145582026605
0.04629046703784687
0.04675337170822534
0.047220905425307595
0.04769311447956067
0.04817004562435628
0.04865174608059984
0.04913826354140584
0.0496296461768199
0.0501259426385881
0.05062720206497398
0.05113347408562372
0.05164480882647996
0.05216125691474476
0.05268286948389221
0.053209698178731134
0.05374179516051845
0.05427921311212363
0.05482200524324487
0.05537022529567732
0.05592392754863409
0.056483166824120426
0.05704799849236163
0.05761847847728525
0.0581946632620581
0.05877660989467868
0.059364375993625464
0.05995801975356172
0.060557599951097336
0.06116317595060831
0.06177480771011439
0.06239255578721554
0.0630164813450877
0.06364664615853857
0.06428311262012396
0.0649259437463252
0.06557520318378844
0.06623095521562633
0.0668932647677826
0.06756219741546042
0.06823781938961503
0.06892019758351117
0.06960939955934628
0.07030549355493974
0.07100854849048914
0.07171863397539403
0.07243582031514798
0.07316017851829945
0.07389178030348245
0.07463069810651728
0.07537700508758245
0.07613077513845827
0.07689208288984285
0.07766100371874128
0.0784376137559287
0.07922198989348798
0.08001420979242287
0.0808143518903471
0.08162249540925057
0.08243872036334307
0.0832631075669765
0.08409573864264626
0.08493669602907272
0.08578606298936345
0.08664392361925709
0.08751036285544966
0.08838546648400417
0.08926932114884421
0.09016201436033265
0.09106363450393598
0.09197427084897535
0.0928940135574651
0.09382295369303975
0.09476118322997015
0.09570879506226986
0.09666588301289256
0.09763254184302148
0.0986088672614517
0.09959495593406621
0.10059090549340688
0.10159681454834095
0.10261278269382436
0.1036389105207626
0.10467529962597022
0.10572205262222992
0.10677927314845222
0.10784706587993674
0.10892553653873611
0.11001479190412347
0.1111149398231647
0.11222608922139635
0.11334835011361032
0.11448183361474643
0.11562665195089389
0.11678291847040283
0.11795074765510685
0.11913025513165793
0.1203215576829745
0.12152477325980425
0.12274002099240229
0.12396742120232632
0.12520709541434957
0.12645916636849308
0.127723758032178
0.12900099561249978
0.13029100556862477
0.13159391562431103
0.13290985478055414
0.1342389533283597
0.13558134286164328
0.1369371562902597
0.1383065278531623
0.13968959313169393
0.14108648906301088
0.142497353953641
0.1439223274931774
0.14536155076810917
0.14681516627579025
0.14828331793854815
0.14976615111793362
0.15126381262911295
0.15277645075540408
0.15430421526295812
0.1558472574155877
0.15740572998974356
0.158979787289641
0.1605695851625374
0.16217528101416276
0.16379703382430438
0.16543500416254742
0.1670893542041729
0.16876024774621462
0.17044785022367676
0.17215232872591352
0.17387385201317265
0.17561259053330439
0.17736871643863744
0.1791424036030238
0.18093382763905405
0.1827431659154446
0.18457059757459904
0.18641630355034502
0.1882804665858485
0.19016327125170698
0.19206490396422404
0.19398555300386627
0.19592540853390494
0.197884662619244
0.19986350924543644
0.20186214433789082
0.20388076578126973
0.20591957343908243
0.20797876917347324
0.21005855686520797
0.21215914243386005
0.21428073385819865
0.21642354119678064
0.21858777660874845
0.22077365437483593
0.2229813909185843
0.22521120482777013
0.22746331687604782
0.2297379500448083
0.23203532954525638
0.23435568284070896
0.23669923966911605
0.2390662320658072
0.24145689438646528
0.24387146333032994
0.24631017796363325
0.24877327974326957
0.25126101254070227
0.2537736226661093
0.2563113588927704
0.2588744724816981
0.26146321720651505
0.2640778493785802
0.266718627872366
0.26938581415108964
0.27207967229260055
0.27480046901552657
0.27754847370568186
0.28032395844273866
0.28312719802716607
0.28595847000743774
0.2888180547075121
0.2917062352545872
0.2946232976071331
0.2975695305832044
0.3005452258890364
0.3035506781479268
0.3065861849294061
0.3096520467787002
0.3127485672464872
0.31587605291895204
0.31903481344814155
0.322225161582623
0.3254474131984492
0.3287018873304337
0.33198890620373805
0.33530879526577545
0.3386618832184332
0.34204850205061754
0.3454689870711237
0.34892367694183496
0.35241291371125333
0.35593704284836586
0.3594964132768495
0.363091377409618
0.3667222911837142
0.3703895140955513
0.37409340923650686
0.37783434332887195
0.38161268676216065
0.38542881362978226
0.3892831017660801
0.3931759327837409
0.3971076921115783
0.40107876903269407
0.405089556723021
0.4091404522902512
0.4132318568131537
0.41736417538128523
0.4215378171350981
0.42575319530644906
0.43001072725951356
0.43431083453210867
0.43865394287742976
0.4430404823062041
0.44747088712926614
0.4519455960005588
0.45646505196056436
0.46102970248017
0.4656399995049717
0.47029639950002144
0.47499936349502164
0.47974935712997185
0.48454685070127157
0.4893923192082843
0.4942862424003671
0.4992291048243708
0.5042213958726145
0.5092636098313407
0.5143562459296541
0.5194998083889507
0.5246948064728402
0.5299417545375685
0.5352411720829442
0.5405935838037736
0.5459995196418114
0.5514595148382295
0.5569741099866118
0.5625438510864779
0.5681692895973427
0.5738509824933161
0.5795894923182493
0.5853853872414317
0.5912392411138461
0.5971516335249846
0.6031231498602344
0.6091543813588367
0.615245925172425
0.6213983844241493
0.6276123682683908
0.6338884919510748
0.6402273768705855
0.6466296506392913
0.6530959471456843
0.6596269066171412
0.6662231756833126
0.6728854074401457
0.6796142615145472
0.6864104041296927
0.6932745081709896
0.7002072532526995
0.7072093257852266
0.7142814190430788
0.7214242332335097
0.7286384755658448
0.7359248603215033
0.7432841089247183
0.7507169500139654
0.7582241195141051
0.7658063607092461
0.7734644243163386
0.7811990685595019
0.789011059245097
0.7969011698375479
0.8048701815359234
0.8129188833512826
0.8210480721847955
0.8292585529066434
0.8375511384357098
0.8459266498200669
0.8543859163182677
0.8629297754814503
0.8715590732362648
0.8802746639686274
0.8890774106083137
0.8979681847143969
0.9069478665615408
0.9160173452271562
0.9251775186794278
0.9344292938662221
0.9437735868048843
0.9532113226729332
0.9627434358996625
0.9723708702586591
0.9820945789612456
0.9919155247508581
1.0018346799983666
1.0118530267983503
Notice that there is no discernible pattern. If you ran Ibu's code, you would never know how long the fade was. You would have to grab a timer and guess and check 2 seconds. Nonetheless, Ibu's code did make a pretty nice fade in (it probably works for fade out. I don't know because I didn't use a fade out yet). My code will also work for a fade out. Let's just say you wanted 2 seconds for a fade out. You can do that with my code. Here is how it would look:
//Fade out. (Continued from the fade in.
function Timer2()
{
element.style.opacity = Op2;
Op2 = Op2 - .01;
console.log(Op2); //Option, but I recommend it for testing purposes.
if (Op2 < 0)
{
clearInterval(foo2);
}
}
All I did was change the opacity to 1 (or fully opaque). I changed the opacity increment to -.01 so it would start turning invisible. Lastly, I changed the opacity limit to 0. When it hits the opacity limit, the timer will stop. Same as the last one, except it used 1 instead of 0. When you run the code, here is what the console log should relatively look like.
.99
0.98
0.97
0.96
0.95
0.94
0.9299999999999999
0.9199999999999999
0.9099999999999999
0.8999999999999999
0.8899999999999999
0.8799999999999999
0.8699999999999999
0.8599999999999999
0.8499999999999999
0.8399999999999999
0.8299999999999998
0.8199999999999998
0.8099999999999998
0.7999999999999998
0.7899999999999998
0.7799999999999998
0.7699999999999998
0.7599999999999998
0.7499999999999998
0.7399999999999998
0.7299999999999998
0.7199999999999998
0.7099999999999997
0.6999999999999997
0.6899999999999997
0.6799999999999997
0.6699999999999997
0.6599999999999997
0.6499999999999997
0.6399999999999997
0.6299999999999997
0.6199999999999997
0.6099999999999997
0.5999999999999996
0.5899999999999996
0.5799999999999996
0.5699999999999996
0.5599999999999996
0.5499999999999996
0.5399999999999996
0.5299999999999996
0.5199999999999996
0.5099999999999996
0.49999999999999956
0.48999999999999955
0.47999999999999954
0.46999999999999953
0.4599999999999995
0.4499999999999995
0.4399999999999995
0.4299999999999995
0.4199999999999995
0.4099999999999995
0.39999999999999947
0.38999999999999946
0.37999999999999945
0.36999999999999944
0.35999999999999943
0.3499999999999994
0.3399999999999994
0.3299999999999994
0.3199999999999994
0.3099999999999994
0.2999999999999994
0.28999999999999937
0.27999999999999936
0.26999999999999935
0.25999999999999934
0.24999999999999933
0.23999999999999932
0.22999999999999932
0.2199999999999993
0.2099999999999993
0.1999999999999993
0.18999999999999928
0.17999999999999927
0.16999999999999926
0.15999999999999925
0.14999999999999925
0.13999999999999924
0.12999999999999923
0.11999999999999923
0.10999999999999924
0.09999999999999924
0.08999999999999925
0.07999999999999925
0.06999999999999926
0.059999999999999255
0.04999999999999925
0.03999999999999925
0.02999999999999925
0.019999999999999248
0.009999999999999247
-7.528699885739343e-16
-0.010000000000000753
As you can see, the .01 pattern still exists in the fade out. Both fades are smooth and precise. I hope these codes helped you or gave you insight on the topic. If you have any additions or suggestions let me know. Thank you for taking the time to view this!

I think i get the problem :
Once you make the div fade out you aren't exiting the function : fadeout calls itself again over even after opacity has become 0
if(element.style.opacity < 0.0) {
return;
}
And do the same for fadein too

let count=0;
let text = document.getElementById('heading');
let btn = document.getElementById('btn');
btn.addEventListener('click', function(){
if(count%2==0){
text.style.opacity="0.1";
unfade(text);
text.innerText="Welcome to Javascript </>";
text.style.color="forestgreen";
}//end of if
else{ text.style.opacity="0.1";
unfade(text);
text.innerText="Hello javascript";
text.style.color="blueviolet";
}//end of else
count++;//for toggling the text
});
//function for fade effect--------
function unfade(element) {
var op = 0.1; // initial opacity
element.style.display = 'block';
var timer = setInterval(function () {
if (op >= 1){
clearInterval(timer);
}
element.style.opacity = op;
element.style.filter = 'alpha(opacity=' + op * 100 + ")";
op += op * 0.1;
}, 30);
}
<h1 style="color:blueviolet" id="heading">Hello javascript</h1>
<button id="btn">Click me</button>

The following javascript will fade in an element from opacity 0 to whatever the opacity value was at the time of calling fade in. You can also set the duration of the animation which is nice:
function fadeIn(element) {
var duration = 0.5;
var interval = 10;//ms
var op = 0.0;
var iop = element.style.opacity;
var timer = setInterval(function () {
if (op >= iop) {
op = iop;
clearInterval(timer);
}
element.style.opacity = op;
op += iop/((1000/interval)*duration);
}, interval);
}
*Based on IBUs answer but modified to account for previous opacity value and ability to set duration, also removed irrelevant CSS changes it was making

My answer is based on Gb01's answer (thank you!). I wanted to abstract out the logic so that we could simply pass an element to a function and have that element fade toggle, fade in, or fade out.
POD
To use the code below:
Elements that can be faded should be given the fadeable class.
Fade in/out with fadeInElement(element) and fadeOutElement(element).
Turn fade on/off with toggle, toggleElementFade(element).
Improvements Over Gb01's answer
Bug Fix: Gb01's answer only worked because id-based CSS rules take precedence over class-based CSS rules, and if you removed #slideSource from #slideSource.fade, it would cease to work.
Bug Fix: Gb01's answer provides for when you start with the element displayed. What if you want to start with it hidden? Completely different code is required
Code: Elements Begin Being Displayed
function fadeInElement(element) {
element.classList.remove('fade');
}
function fadeOutElement(element) {
element.classList.add('fade');
}
function toggleElementFade(element) {
element.classList.toggle('fade');
}
document.getElementById('fade-toggle').onclick = function () {
toggleElementFade(document.getElementsByClassName('fadeable')[0]);
}
document.getElementById('fade-in').onclick = function () {
fadeInElement(document.getElementsByClassName('fadeable')[0]);
}
document.getElementById('fade-out').onclick = function () {
fadeOutElement(document.getElementsByClassName('fadeable')[0]);
}
.fadeable {
opacity: 1;
transition: opacity 1s;
}
.fade {
opacity: 0 !important;
}
<button id="fade-toggle">Fade Toggle</button>
<button id="fade-in">Fade In</button>
<button id="fade-out">Fade Out</button>
<div class="fadeable">Whatever you want here - images or text</div>
Code: Elements Begin Being Hidden
function fadeInElement(element) {
element.style.removeProperty('display');
setTimeout(function() {
element.classList.remove('fade');
}, 10);
}
function fadeOutElement(element) {
element.classList.add('fade');
}
function toggleElementFade(element) {
element.style.removeProperty('display');
setTimeout(function() {
element.classList.toggle('fade');
}, 10);
}
document.getElementById('fade-toggle').onclick = function () {
toggleElementFade(document.getElementsByClassName('fadeable')[0]);
}
document.getElementById('fade-in').onclick = function () {
fadeInElement(document.getElementsByClassName('fadeable')[0]);
}
document.getElementById('fade-out').onclick = function () {
fadeOutElement(document.getElementsByClassName('fadeable')[0]);
}
.fadeable {
opacity: 1;
transition: opacity 1s;
}
.fade {
opacity: 0 !important;
}
<button id="fade-toggle">Fade Toggle</button>
<button id="fade-in">Fade In</button>
<button id="fade-out">Fade Out</button>
<div class="fadeable fade" style="display:none;">Whatever you want here - images or text</div>

That was actually quite simple .
for ex: if you are hiding the text or changing it's color .
document.getElementById('availabletoday').style.color = '#f4f6f7';
make a css property like this
#availabletoday{
transition: 1s;
}
depending upon your event listener when the JavaScript executes it will transition in 1s . really easy to change the delay .
Let me know if this helps