Develop Reference

CSS translation animation doesn't work when parent is shown

There are similar questions like this and this, but don't address this situation.
The goal is to slide a menu onto the screen with CSS translation when its parent is shown. However, showing the parent then applying the CSS class to trigger the translation happens instantly instead of over time. Effectively, there's no animation.
JavaScript could be used to slide the child element onto the screen, but the goal is to keep as much of the animation logic in CSS.
Setting the opacity to 0 doesn't work because we need the menu and its parent to not take any space or be part of the layout.
Codepen: https://codepen.io/Crashalot/pen/YzXmjYj
function toggleSidebar() {
$("#sidebar").toggleClass("show");
}
$("#button").on("click", function() {
toggleSidebar();
});
body {
margin: 0;
padding: 0;
}
#button {
position: fixed;
top: 0;
left: 200px;
width: 150px;
height: 50px;
background: yellow;
display: flex;
justify-content: center;
align-items: center;
z-index: 8;
cursor: pointer;
}
#sidebar {
display: none;
}
#sidebar.show {
display: block;
}
.overlay {
position: fixed;
width: 100vw;
height: 100vh;
background: red;
z-index: -1;
}
.menuBox {
width: 200px;
height: 100vh;
background: blue;
transition: 0.3s ease-in-out;
transform: translate(-100%);
}
#sidebar.show .menuBox {
transform: translate(0);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="sidebar">
<div class="overlay"></div>
<div class="menuBox"></div>
</div>
<div id="button">CLICK ME</div>

You can't animate display: none; Set opacity to 0 and then 1 on toggle class. Here's the CodePen for you. ;)
I added a button for the toggle event. Let me know if you need any more help!
enter link description here
$(".btn").on("click", toggleSidebar);
function toggleSidebar() {
$("#sidebar").toggleClass("show");
}
body {
margin: 0;
padding: 0;
}
#sidebar {
opacity: 0;
transition: all 300ms ease-in-out;
}
#sidebar.show {
display: block;
opacity: 1;
}
.overlay {
position: fixed;
width: 100vw;
height: 100vh;
background: red;
z-index: -1;
}
.menuBox {
width: 200px;
height: 100vh;
background: blue;
transition: 300ms ease-in-out;
-webkit-transform: translate(-100%);
}
#sidebar.show .menuBox {
-webkit-transform: translate(0);
}
.btn {
position: absolute;
top: 10px;
left: 20px;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="sidebar">
<div class="overlay"></div>
<div class="menuBox"></div>
</div>
<button class="btn">Click</button>

You need to consider an animation. The animation will run automatically when the element appear on the screen
function toggleSidebar() {
$("#sidebar").toggleClass("show");
}
$("#button").on("click", function() {
toggleSidebar();
});
body {
margin: 0;
padding: 0;
}
#button {
position: fixed;
top: 0;
left: 200px;
width: 150px;
height: 50px;
background: yellow;
display: flex;
justify-content: center;
align-items: center;
z-index: 8;
cursor: pointer;
}
#sidebar {
display: none;
}
#sidebar.show {
display: block;
}
.overlay {
position: fixed;
width: 100vw;
height: 100vh;
background: red;
z-index: -1;
}
.menuBox {
width: 200px;
height: 100vh;
background: blue;
transform: translate(-100%);
animation: show 0.3s ease-in-out forwards;
}
#keyframes show {
to {
transform: translate(0);
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="sidebar">
<div class="overlay"></div>
<div class="menuBox"></div>
</div>
<div id="button">CLICK ME</div>
updating display to a value other than none will start all animations applied to the element by the animation-name property, as well as all animations applied to descendants with display other than none. ref

I think you should define the action for your function called. When load page or on click like below:
$(document).ready(function () {
$('#sidebar').on('click', function () {
$(this).toggleClass('show');
});
});

Only one out of five divs transitions correctly

After clicking the button the elements should move to their second positions. It only seems to work with the last element where I used !important which I don't want to use. Here is my code:
let ruch = document.querySelectorAll('.menu');
let myArray = Array.from(ruch);
let btn = document.getElementById('btn');
btn.addEventListener('click', function () {
myArray.forEach(function (item) {
if (item == myArray[0]) {
item.classList.add('run1');
} else if (item == myArray [4]) {
item.classList.add('run2');
} else {
item.classList.add('run');
}
});
});
body {
background-color: #302e2e;
font-size:22px;
}
#btn{
position: absolute;
left: 914px;
top: 180px;
}
.wrapper{
position: relative;
width:600px;
margin: 0 auto;
}
.container{
position:absolute;
top:250px;
width:0px;
}
.menu{
padding:5px;
border:1px solid #323232;
width:100px;
height:100px;
background:#46f4a0;
border-radius:20px;
position: absolute;
box-sizing: border-box;
}
.menu:nth-child(2){
left:105px;
}
.menu:nth-child(3){
left:210px;
}
.menu:nth-child(4){
left:315px;
}
.menu:nth-child(5){
left:420px;
}
.run{
opacity: 0;
transition:3s ease-in-out;
z-index: -1;
top:110px;
}
.run1{
opacity: 0;
transition:3s ease-in-out;
z-index: -1;
left:-110px;
}
.run2{
opacity: 0;
transition:3s ease-in-out;
z-index: -1;
left:530px!important;
}
<button id="btn">
Kliknij
</button>
<div class="wrapper">
<div class="container ">
<div class="menu ">About</div>
<div class="menu ">My Projets</div>
<div class="menu ">Some stuff</div>
<div class="menu ">Werid shits</div>
<div class="menu ">Contact</div>
</div>
</div>
Thanks for your help

Like this? (complementary CodePen)
let menuItems = Array.from(document.querySelectorAll(".menu"));
document.getElementById("btn").addEventListener("click", function() {
menuItems[0].classList.add("run1");
menuItems[4].classList.add("run2");
menuItems.slice(1, 4).forEach(function(item) {
item.classList.add("run");
});
});
body {
background-color: #302e2e;
font-size: 22px;
}
#btn {
position: absolute;
left: 914px;
top: 180px;
}
.wrapper {
position: relative;
width: 600px;
margin: 0 auto;
}
.container {
position: absolute;
top: 250px;
width: 0px;
}
.menu {
padding: 5px;
border: 1px solid #323232;
width: 100px;
height: 100px;
background: #46f4a0;
border-radius: 20px;
position: absolute;
box-sizing: border-box;
}
.menu:nth-child(2) {
left: 105px;
}
.menu:nth-child(3) {
left: 210px;
}
.menu:nth-child(4) {
left: 315px;
}
.menu:nth-child(5) {
left: 420px;
}
.menu.run {
opacity: 0;
transition: 3s ease-in-out;
transform: translateY(110px);
}
.menu.run1 {
opacity: 0;
transition: 3s ease-in-out;
transform: translateX(-110px);
}
.menu.run2 {
opacity: 0;
transition: 3s ease-in-out;
transform: translateX(110px);
}
<button id="btn">Kliknij</button>
<div class="wrapper">
<div class="container">
<div class="menu">About</div>
<div class="menu">My Projets</div>
<div class="menu">Some stuff</div>
<div class="menu">Werid shits</div>
<div class="menu">Contact</div>
</div>
</div>
Please also look into your CSS again. You should avoid working with absolute positioning and pixel values only since it will look different on every device.

U need to move transition to '.menu' and it should look like that:transition:3s transform ease-in-out;. And in '.run', '.run1', '.run2' when left replace with: transform: translateX(/*value*/px);. And when top replace with: transform: translateY(/*value*/px);.

Div slide from top not slide to reveal

I want the contents of a div to slide down from the top. All of the methods I have tried seem to 'reveal' the contents which is almost static. I want to slide down from off the edge of the screen and push the content too. How would I do this? Jsfiddle here
html
<div id="dolphin">
<div id="lizard"><img src="http://www.beardeddragon.co/image/cache/data/blackhat-500x500.jpg"></div>
</div>
<div id="content"></div>
css
#lizard {
padding:50px;
display:none;
}
#dolphin {
position: fixed;
width: 100%;
background-color: green;
}
#content {
height: 2000px;
}
js
$(document).ready(function(){
$("#dolphin").click(function(){
$("#lizard").stop().slideToggle("fast");
});
});

You can move things with negative margins to create a slide effect instead of a reveal effect.
This is a very rough example but you can see how it's originally hidden with margin-top: -100%; and revealed by setting margin-top to 0;
$(".slide-button").click(function(){
$(".lizard").toggleClass('slideit');
});
html, body {margin: 0; padding: 0;}
div {
text-align: center;
}
.slide-button {
position: fixed;
top: 0; right: 0; left: 0;
z-index: 10;
display: flex;
justify-content: center;
align-items: center;
height: 20px;
background-color: green;
cursor: pointer;
}
.lizard {
width: 100%;
padding-top: 20px;
overflow: hidden;
background-color: green;
transition: all 0.5s ease;
}
.lizard img {
margin-top: -100%;
transition: all 0.5s ease;
opacity: 0;
}
.lizard.slideit img {
margin-top: 10px;
opacity: 1;
}
.content {
height: 1000px;
background-color: green;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="slide-button">slide it</div>
<div class="lizard">
<img src="http://www.beardeddragon.co/image/cache/data/blackhat-500x500.jpg">
</div>
<div class="content"></div>
fiddle
https://jsfiddle.net/Hastig/qjfgsrL0/1/

jQuery Add Markers

I'm currently trying to make a website that displays markers with its own specific text.
When a user clicks on the marker, it displays the text.
I've copied some code online and trying to mess around with it. Unfortunately, I'm not too experience with javascript. I was wondering if anyone would be able to help.
This is what I have so far:
HTML (I don't think there's any problems here):
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>MarkerWeb</title>
<link rel="stylesheet" href="style.css">
<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
</head>
<body>
<div id="container">
<div id="image-wrapper" data-captions='{"coords": [{"top":250,"left":200,"text":"iMac 1"},{"top":250,"left":540,"text":"iMac 2"}]}'>
<!-- layout.jpg is just a picture of a layout/floorplan -->
<img src="layout.jpg" alt=""/>
</div>
</div>
</body>
<script type="text/javascript" src="script.js"></script>
</html>
Javascript (The part I'm having a hard time with):
var Markers = {
fn: {
addMarkers: function() {
var target = $('#image-wrapper');
var data = target.attr('data-captions');
var captions = $.parseJSON(data);
var coords = captions.coords;
for (var i = 0; i < coords.length; i++) {
var obj = coords[i];
var top = obj.top;
var left = obj.left;
var text = obj.text;
$('<div class="marker"><div class="pin"><span class="popuptext" id="myPopup">' + text + '</span></div><div class="pin-effect"></div></div>').css({
top: top,
left: left
}).appendTo(target);
}
},
//This is the part I'm having trouble with.
showBeaconInfo: function() {
$('body').on('click', '.marker', function() {
var $marker = $(this),
$caption = $('popuptext', $marker);
if ($caption.is(':hidden')) {
$caption.show();
} else {
$caption.toggle("show");
}
});
}
},
init: function() {
this.fn.addMarkers();
this.fn.showBeaconInfo();
}
};
function clickBeacon() {
var popup = document.getElementById("myPopup");
popup.classList.toggle("show");
}
$(function() {
Markers.init();
});
CSS (I don't think there's any problems here):
body {
background: #e6e6e6;
}
#image-wrapper {
width: 800px;
height: 760px;
position: relative;
margin: 2em auto;
background: #f6f6f6;
border: 2px solid #ddd;
}
#image-wrapper img {
display: block;
margin: 25px auto;
}
.map-bg {
background: url(images/map-bg.jpg) no-repeat;
background-position: 0px 0px;
background-size: auto;
width: 100%;
height: 440px; /*adjust to the height of your image*/
position: relative;
}
.marker {
width: 100px;
height: 100px;
position: absolute;
/*top: 130px; /*positions our marker*/
/*left: 200px; /*positions our marker*/
display: block;
}
.pin {
width: 20px;
height: 20px;
position: relative;
top: 38px;
left: 38px;
background: rgba(5, 124, 255, 1);
border: 2px solid #FFF;
border-radius: 50%;
z-index: 1000;
cursor: pointer;
display: inline-block;
}
.pin-effect {
width: 100px;
height: 100px;
position: absolute;
top: 0;
display: block;
background: rgba(5, 124, 255, 0.6);
border-radius: 50%;
opacity: 0;
animation: pulsate 2400ms ease-out infinite;
}
#keyframes pulsate {
0% {
transform: scale(0.1);
opacity: 0;
}
50% {
opacity: 1;
}
100% {
transform: scale(1.2);
opacity: 0;
}
}
/* The actual popup (appears on top) */
.pin .popuptext {
visibility: hidden;
width: 160px;
background-color: #555;
color: #fff;
text-align: center;
border-radius: 6px;
padding: 8px 0;
position: absolute;
z-index: 1;
bottom: 125%;
left: 50%;
margin-left: -80px;
}
/* Popup arrow */
.pin .popuptext::after {
content: "";
position: absolute;
top: 100%;
left: 50%;
margin-left: -5px;
border-width: 5px;
border-style: solid;
border-color: #555 transparent transparent transparent;
}
/* Toggle this class when clicking on the popup container (hide and show the popup) */
.pin .show {
visibility: visible;
-webkit-animation: fadeIn 1s;
animation: fadeIn 1s
}
/* Add animation (fade in the popup) */
#-webkit-keyframes fadeIn {
from {opacity: 0;}
to {opacity: 1;}
}
#keyframes fadeIn {
from {opacity: 0;}
to {opacity:1 ;}
}

You need to update your showBeaconInfo function in 2 ways:
1) Fix the selector for $caption to grab the class popuptext by adding a period
2) Using the jquery function toggleClass to add or remove the class "show" on the popuptext, the css is setup to either use visibility: hidden or visibility: visible
showBeaconInfo: function() {
$('body').on('click', '.marker', function() {
var $marker = $(this);
var $caption = $('.popuptext', $marker); //needs period to indicate class
$caption.toggleClass('show'); //adding the class "show" will display the text
});
}
For Example:
var Markers = {
fn: {
addMarkers: function() {
var target = $('#image-wrapper');
var data = target.attr('data-captions');
var captions = $.parseJSON(data);
var coords = captions.coords;
for (var i = 0; i < coords.length; i++) {
var obj = coords[i];
var top = obj.top;
var left = obj.left;
var text = obj.text;
$('<div class="marker"><div class="pin"><span class="popuptext" id="myPopup">' + text + '</span></div><div class="pin-effect"></div></div>').css({
top: top,
left: left
}).appendTo(target);
}
},
//This is the part I'm having trouble with.
showBeaconInfo: function() {
$('body').on('click', '.marker', function() {
var $marker = $(this);
var $caption = $('.popuptext', $marker); //needs period to indicate class
$caption.toggleClass('show'); //adding the class "show" will display the text
});
}
},
init: function() {
this.fn.addMarkers();
this.fn.showBeaconInfo();
}
};
function clickBeacon() {
var popup = document.getElementById("myPopup");
popup.classList.toggle("show");
}
$(function() {
Markers.init();
});
body {
background: #e6e6e6;
}
#image-wrapper {
width: 800px;
height: 760px;
position: relative;
margin: 2em auto;
background: #f6f6f6;
border: 2px solid #ddd;
}
#image-wrapper img {
display: block;
margin: 25px auto;
}
.map-bg {
background: url(images/map-bg.jpg) no-repeat;
background-position: 0px 0px;
background-size: auto;
width: 100%;
height: 440px;
/*adjust to the height of your image*/
position: relative;
}
.marker {
width: 100px;
height: 100px;
position: absolute;
/*top: 130px; /*positions our marker*/
/*left: 200px; /*positions our marker*/
display: block;
}
.pin {
width: 20px;
height: 20px;
position: relative;
top: 38px;
left: 38px;
background: rgba(5, 124, 255, 1);
border: 2px solid #FFF;
border-radius: 50%;
z-index: 1000;
cursor: pointer;
display: inline-block;
}
.pin-effect {
width: 100px;
height: 100px;
position: absolute;
top: 0;
display: block;
background: rgba(5, 124, 255, 0.6);
border-radius: 50%;
opacity: 0;
animation: pulsate 2400ms ease-out infinite;
}
#keyframes pulsate {
0% {
transform: scale(0.1);
opacity: 0;
}
50% {
opacity: 1;
}
100% {
transform: scale(1.2);
opacity: 0;
}
}
/* The actual popup (appears on top) */
.pin .popuptext {
visibility: hidden;
width: 160px;
background-color: #555;
color: #fff;
text-align: center;
border-radius: 6px;
padding: 8px 0;
position: absolute;
z-index: 1;
bottom: 125%;
left: 50%;
margin-left: -80px;
}
/* Popup arrow */
.pin .popuptext::after {
content: "";
position: absolute;
top: 100%;
left: 50%;
margin-left: -5px;
border-width: 5px;
border-style: solid;
border-color: #555 transparent transparent transparent;
}
/* Toggle this class when clicking on the popup container (hide and show the popup) */
.pin .show {
visibility: visible;
-webkit-animation: fadeIn 1s;
animation: fadeIn 1s
}
/* Add animation (fade in the popup) */
#-webkit-keyframes fadeIn {
from {
opacity: 0;
}
to {
opacity: 1;
}
}
#keyframes fadeIn {
from {
opacity: 0;
}
to {
opacity: 1;
}
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="container">
<div id="image-wrapper" data-captions='{"coords": [{"top":250,"left":200,"text":"iMac 1"},{"top":250,"left":540,"text":"iMac 2"}]}'>
<!-- layout.jpg is just a picture of a layout/floorplan -->
<img src="layout.jpg" alt="" />
</div>
</div>

making a toggle button to change panels

I have two panels at the top of my application and one button at the button. By default only panel one must be visible, but by clicking on the button panel one fades away, and panel two fades in. I created the layout, but I do not know how to achieve it.
$(".panel2").hide();
$(document).ready(function() {
$(".grid-button").on("click", function() {
$(".grid").toggleClass("open close");
});
});
div.app {
margin:50px auto;
width: 400px;
height: 400px;
border-radius:10px;
overflow: hidden;
position: relative;
}
div.app > .blur {
width: 100%;
height: 100%;
background: url(http://goo.gl/0VTd9W);
-webkit-filter: blur(5px);
}
div.mainSection, div.dashboard{
position: absolute;
left: 0px;
text-align:center;
color:#fff;
font-size:20px;
}
div.mainSection{
width:100%;
height:85%;
background:rgba(0,0,0,0.5);
top:0;
}
div.dashboard{
width:100%;
height:15%;
background:rgba(255,0,0,0.5);
bottom:0;
}
div.mainSection > .panel1,
div.mainSection > .panel2 {
width: 100%;
Height: 100%;
Background: rgba(0, 0, 0, 0.5);
position: absolute;
left: 0px;
top: 0px;
}
.grid-button {
background: none;
border: none;
padding: 3px;
width: 100%;
}
.grid {
display: inline-block;
height: 4px;
position: relative;
width: 32px;
transition: all 0.3s ease-in-out;
}
.grid:after, .grid:before {
content: '';
position: absolute;
background-color: #FFF;
display: inline-block;
height: 4px;
left: 0;
width: 32px;
transition: all 0.3s ease-in-out;
}
.grid.open {
background-color: #FFF;
}
.grid.open:after {
top: 10px;
}
.grid.open:before {
top: -10px;
}
.grid.close {
background-color: transparent;
transform: scale(0.9);
}
.grid.close:after, .grid.close:before {
top: 0;
transform-origin: 50% 50%;
}
.grid.close:before {
transform: rotate(135deg);
}
.grid.close:after {
transform: rotate(45deg);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="app">
<div class="blur"></div>
<div class="mainSection">
<div class="panel1">Panel1</div>
<div class="panel2">Panel2</div>
</div>
<div class="dashboard">
<div class="grid-button">
<span class="grid open"></span>
</div>
</div>
</div>
First of all since I did $('.panel2').hide();, in page load first it loads the panel then hides it. How can I make it invisible from the beginning?
Secondly how can I make the panel2 visible only by pressing the button?
And finally is there anyway to add some transitions effects for changing panels?

You may try:
$(".grid-button").on("click", function() {
var visibleObj = $('.mainSection div:visible');
var inVisibleObj = $('.mainSection div:hidden');
visibleObj.fadeOut(500, function() {
inVisibleObj.fadeIn(500);
});
});
While for the visibility you need:
<div class="panel2" style="display: none;">Panel2</div&gt
The running snippet:
$(function () {
$(".grid-button").on("click", function() {
var visibleObj = $('.mainSection div:visible');
var inVisibleObj = $('.mainSection div:hidden');
visibleObj.fadeOut(500, function() {
inVisibleObj.fadeIn(500);
});
});
});
div.app {
margin:50px auto;
width: 400px;
height: 400px;
border-radius:10px;
overflow: hidden;
position: relative;
}
div.app > .blur {
width: 100%;
height: 100%;
background: url(http://goo.gl/0VTd9W);
-webkit-filter: blur(5px);
}
div.mainSection, div.dashboard{
position: absolute;
left: 0px;
text-align:center;
color:#fff;
font-size:20px;
}
div.mainSection{
width:100%;
height:85%;
background:rgba(0,0,0,0.5);
top:0;
}
div.dashboard{
width:100%;
height:15%;
background:rgba(255,0,0,0.5);
bottom:0;
}
div.mainSection > .panel1,
div.mainSection > .panel2 {
width: 100%;
Height: 100%;
Background: rgba(0, 0, 0, 0.5);
position: absolute;
left: 0px;
top: 0px;
}
.grid-button {
background: none;
border: none;
padding: 3px;
width: 100%;
}
.grid {
display: inline-block;
height: 4px;
position: relative;
width: 32px;
transition: all 0.3s ease-in-out;
}
.grid:after, .grid:before {
content: '';
position: absolute;
background-color: #FFF;
display: inline-block;
height: 4px;
left: 0;
width: 32px;
transition: all 0.3s ease-in-out;
}
.grid.open {
background-color: #FFF;
}
.grid.open:after {
top: 10px;
}
.grid.open:before {
top: -10px;
}
.grid.close {
background-color: transparent;
transform: scale(0.9);
}
.grid.close:after, .grid.close:before {
top: 0;
transform-origin: 50% 50%;
}
.grid.close:before {
transform: rotate(135deg);
}
.grid.close:after {
transform: rotate(45deg);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="app">
<div class="blur"></div>
<div class="mainSection">
<div class="panel1">Panel1</div>
<div class="panel2" style="display: none;">Panel2</div>
</div>
<div class="dashboard">
<div class="grid-button">
<span class="grid open"></span>
</div>
</div>
</div>

To make one of the panels hidden in the first place, I'd use a css class called hidden:
.hidden{
display : none;
}
Which simply makes what it sounds like, hiding the element.
Than, I'd set this class in the HTML decleration:
<div class="panel2 hidden">Panel2</div>
That will hide panel2 on page load, and by that you don't have to hide it using js code.
Than, I'd use a helper css class called panel that stands to be a panel identifier (you can either use the data attribute, or any other way of identifying those elements).
For 5 panels, it would look like this:
<div class="panel panel1">Panel1</div>
<div class="panel panel2 hidden">Panel2</div>
<div class="panel panel3 hidden">Panel3</div>
<div class="panel panel4 hidden">Panel4</div>
<div class="panel panel5 hidden">Pane5</div>
At last, to make this work for any number of panels you want (not necesseraly 2), I'd use a "carousel" effect to toggle the panels visibility, while having a way to keep track with them (adding and removing the hidden class), and use the fadeIn/fadeOut effect. (again, instead of identifying the panels using the panel1,panel2,panel3... classes, you can always use the data attribute (please read more about it in jQuery docs), or in any other way).
var currentPanel = 1;
$(".grid-button").on("click", function() {
$(".grid").toggleClass("open close");
$(".panel"+currentPanel).fadeOut("normal", function(){
$(this).addClass('hidden');
});
currentPanel = currentPanel >= $(".panel").length ? 1 : currentPanel+1;
$(".panel"+currentPanel).fadeIn().removeClass('hidden');
});
Just note that the hidden class actually "looses" it's functionality after the first click, since jQuery changes the display property inline, but I think that it might not be harmful to keep them anyway (it will be easier to track them).
You can see an example here: https://jsfiddle.net/j79y5kdb/3/