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How to know the logic of multilevel menu event bubbling

I'm trying to understand the logic happening in my basic multilevel menu click event. I understood what happening on clicking on "About" menu in the navigation. And it works as per my expecation of code. But when i click on "Profile" menu (Submenu of "About" menu), JS makes it's sublevel menu "display:none". I tried to think in the aspect of even bubbling. But eventhough the bubbling happens here, it should not be working like this. Actually for me, its really complicated to understand how JS works here. It would be a Great Help if anyone can explain with a simple and understandable way. Thank You Very Much in Advance!!!
let menus = document.querySelectorAll(".main-navigation ul li a");
menus.forEach((item) => {
if (item.parentElement.querySelector("ul")) {
item.parentElement.classList.add("has-submenu");
}
});
let submenu = document.querySelectorAll(".has-submenu");
submenu.forEach((item) => {
item.addEventListener("click", (e) => {
e.preventDefault();
let ul = e.target.parentElement.querySelector("ul");
let cs = window.getComputedStyle(ul).display;
if (cs === "none") {
ul.style.cssText = "display:block";
}
else {
ul.style.cssText = "display:none";
}
});
});
.main-navigation ul {list-style:none;margin:0;padding:0;font-family:arial;}
.main-navigation ul li {padding:.35rem;background:#f9f9f9;}
.main-navigation ul li ul {padding-left:1rem;display:none;}
.main-navigation ul li a {display:block;text-decoration:none;}
<div class="main-navigation">
<ul>
<li>Home</li>
<li>About +
<ul>
<li>Profile +
<ul>
<li>History</li>
<li>Management</li>
</ul>
</li>
<li>Vision</li>
<li>Mission</li>
</ul>
</li>
<li>Services +
<ul>
<li>Web Design</li>
<li>Web Development</li>
</ul>
</li>
<li>Contact</li>
</ul>
</div>

Solution
If you add a console.log inside your click handler you will notice that the event for the nested item is called twice.
You probably knew that it could happen and you used preventDefault.
However, preventDefault is for the browser's default effects (for example, it prevents your page to refresh as you put an href attribute) but in your case the double behaviour is from your own custom listener.
This means, you need to add stopPropagation that prevents further propagation of the current event in the capturing and bubbling phases.
Working Demo
let menus = document.querySelectorAll(".main-navigation ul li a");
menus.forEach((item) => {
if (item.parentElement.querySelector("ul")) {
item.parentElement.classList.add("has-submenu");
}
});
let submenu = document.querySelectorAll(".has-submenu");
submenu.forEach((item) => {
item.addEventListener("click", (e) => {
e.preventDefault();
e.stopPropagation();
let ul = e.target.parentElement.querySelector("ul");
let cs = window.getComputedStyle(ul).display;
if (cs === "none") {
ul.style.cssText = "display:block";
} else {
ul.style.cssText = "display:none";
}
});
});
.main-navigation ul {
list-style: none;
margin: 0;
padding: 0;
font-family: arial;
}
.main-navigation ul li {
padding: .35rem;
background: #f9f9f9;
}
.main-navigation ul li ul {
padding-left: 1rem;
display: none;
}
.main-navigation ul li a {
display: block;
text-decoration: none;
}
<div class="main-navigation">
<ul>
<li>Home</li>
<li>About +
<ul>
<li>Profile +
<ul>
<li>History</li>
<li>Management</li>
</ul>
</li>
<li>Vision</li>
<li>Mission</li>
</ul>
</li>
<li>Services +
<ul>
<li>Web Design</li>
<li>Web Development</li>
</ul>
</li>
<li>Contact</li>
</ul>
</div>

Change text color of a span with Javascript while hovering on seperated div

I have a menupoint and underneath it a seperate div / mega menu. I triggered the mega menu to show up via Javascript. When I am hovering over the mega menu, the desired span in the menu should get highlighted with another color and also the background color should change. You can see in the code how I tried to solve it (comments included). Can you please help me. I don´t know why I can´t trigger it via .getElementsByClassName!?
//Showing mega menu on hover over menu point
document.getElementById("menu-item-136").addEventListener("mouseover", mouseOver);
document.getElementById("menu-item-136").addEventListener("mouseout", mouseOut);
function mouseOver() {
document.getElementById("mega-menu").style.display = "block";
}
function mouseOut() {
document.getElementById("mega-menu").style.display = "none";
}
//Let mega menu stay visible when hovering over it
//Style menupoint when hovering over mega menu div (NOT WORKING)!
document.getElementById("mega-menu").addEventListener("mouseover", mouseOver);
document.getElementById("mega-menu").addEventListener("mouseout", mouseOut);
function mouseOver() {
document.getElementById("mega-menu").style.display = "block";
document.getElementsByClassName (".aux-menu-label").style.color = "yellow";
}
function mouseOut() {
document.getElementById("mega-menu").style.display = "none";
document.getElementsByClassName (".aux-menu-label").style.color = "";
}
.menu-item-136 {
background-color: grey;
height: 50px;
}
.menu-item-136:hover {
background-color:green;
}
.aux-menu-label {
color:blue;
}
.mega-menu-1 {
display: none;
background-color: green;
height: 200px;
}
<div>
<li id="menu-item-136" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-has-children menu-item-136 aux-menu-depth-0 aux-menu-root-2 aux-menu-item">
<a href="#" class="aux-item-content">
<span class="aux-menu-label"><i aria-hidden="true" class="services auxicon-list"></i> Leistungen</span>
<span class="aux-submenu-indicator"></span></a>
</div>
<div id="mega-menu" class="mega-menu-1">content</div>
Thanks for your help!

Your code is a bit messy but you are calling your class incorrectly:
This:
document.getElementsByClassName (".aux-menu-label")
Should be this:
document.getElementsByClassName ("aux-menu-label")
Additionally, when using getElementsByClassName you are provided with an array-like object with all elements that have the class you have specified.
With that in mind, you must run a loop to target elements with the styles you want to apply.
The below code is how we will target multiple labels and change them to yellow on hover:
var labels = document.getElementsByClassName("aux-menu-label");
for (var i = 0; i < labels.length; i++) {
labels[i].style.color = "yellow"
}
When you run the snippet below you will see I have used similar code to revert the color back to blue onmouseout.
Learn more about getElementsByClassName here.
//Including this to show you how to target CSS child elements as described in your comment
var childElement = document.querySelector('#menu-item-136 .aux-item-content');
childElement.style.backgroundColor = "white";
console.log(childElement);
//Showing mega menu on hover over menu point
document.getElementById("menu-item-136").addEventListener("mouseover", mouseOver);
document.getElementById("menu-item-136").addEventListener("mouseout", mouseOut);
function mouseOver() {
document.getElementById("mega-menu").style.display = "block";
}
function mouseOut() {
document.getElementById("mega-menu").style.display = "none";
}
//Let mega menu stay visible when hovering over it
//Style menupoint when hovering over mega menu div (NOT WORKING)!
document.getElementById("mega-menu").addEventListener("mouseover", mouseOver);
document.getElementById("mega-menu").addEventListener("mouseout", mouseOut);
function mouseOver() {
document.getElementById("mega-menu").style.display = "block";
var labels = document.getElementsByClassName("aux-menu-label");
for (var i = 0; i < labels.length; i++) {
labels[0].style.color = "yellow"
}
}
function mouseOut() {
document.getElementById("mega-menu").style.display = "none";
var labels = document.getElementsByClassName("aux-menu-label");
for (var i = 0; i < labels.length; i++) {
labels[i].style.color = "blue"
}
}
.menu-item-136 {
background-color: grey;
height: 50px;
}
.menu-item-136:hover {
background-color: green;
}
.aux-menu-label {
color: blue;
}
.mega-menu-1 {
display: none;
background-color: green;
height: 200px;
}
<div>
<li id="menu-item-136" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-has-children menu-item-136 aux-menu-depth-0 aux-menu-root-2 aux-menu-item">
<a href="#" class="aux-item-content">
<span class="aux-menu-label"><i aria-hidden="true" class="services auxicon-list"></i> Leistungen</span>
<span class="aux-submenu-indicator"></span></a>
</div>
<div id="mega-menu" class="mega-menu-1">content</div>
<div>
<li id="menu-item-136" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-has-children menu-item-136 aux-menu-depth-0 aux-menu-root-2 aux-menu-item">
<a href="#" class="aux-item-content">
<span class="aux-menu-label"><i aria-hidden="true" class="services auxicon-list"></i> Leistungen</span>
<span class="aux-submenu-indicator"></span></a>
</div>
<div id="mega-menu" class="mega-menu-1">content</div>
EDIT: I've included the following javascript to show you how to target child elements and apply CSS to them. The code below will target the child of #menu-item-136 and change its background color to white. Run the snippet to see.
var childElement = document.querySelector('#menu-item-136 .aux-item-content');
childElement.style.backgroundColor = "white";
console.log(childElement);

In your code
If we add some margin to megamenu wrapper This will be not working
and menu close when pointer out from menu item.
I have fixed that isseue
Its Looks like with WordPress menu. Please check below example and its will be helpful to use multiple mega-menues You need to map megamenu data id with menu class item.
codepen example
[].forEach.call(document.querySelectorAll('nav > ul > li'), function (link) {
link.addEventListener('mouseover', coloringHandler);
link.addEventListener('mouseout', decoloringHandler);
});
[].forEach.call(document.querySelectorAll('.megamenu'), function (menu) {
menu.addEventListener('mouseover', megamenuHover );
});
var state = false;
function coloringHandler(){
state = false;
hideAllMegamenu();
// add class to current hover element
this.classList.add('active');
var Classes = this.classList; // getting all class list
Classes.forEach(name => {
var megaMenu = document.querySelectorAll('[data-id="'+name+'"]'); // check if have any mached elements with class name
if(megaMenu.length == 1 ){
megaMenu[0].classList.add('active');
state = true;
megaMenu[0].addEventListener('mouseover', megamenuHover );
megaMenu[0].addEventListener('mouseout', megamenuHoverOut );
return;
}
});
}
function decoloringHandler(){
if( state == false ){
this.classList.remove('active');
hideAllMegamenu();
}
}
function hideAllMegamenu(){
// change elemets as you want
[].forEach.call(document.querySelectorAll('nav > ul > li'), function (li) {
li.classList.remove("active");
});
// .megamenu is common class
[].forEach.call(document.querySelectorAll('.megamenu'), function (menues) {
menues.classList.remove('active');
})
}
function megamenuHover() {
this.classList.add('in-hover');
}
function megamenuHoverOut() {
hideAllMegamenu();
}
nav ul{
display:flex;
list-style:none;
}
li{
margin:0px 10px;
}
a{
background:green;
display:block;
color:white;
padding:10px 20px;
}
ul li.active a{
background:red;
}
.megamenu{
background: red;
height:200px;
pointer-events: none;
opacity:0;
position:absolute;
width:100%;
padding:20px;
color:#fff;
transition:all .5s ease;
transform:translateY(50px);
}
.megamenu.active{
opacity:1;
pointer-events: all;
transform:translateY(0px);
}
<h1>Hover over the menu Items</h1>
<nav>
<ul>
<li class="menu-item-136">
<span>Home</span>
</li>
<li class="menu-item-137">
<span>Contact us</span>
</li>
<li class="menu-item-138">
<span>Danushka</span>
</li>
<li class="menu-item-139">
<span>About us</span>
</li>
</ul>
</nav>
<div class="megamenu" data-id="menu-item-137">
Lorem ipsum dolor sit amet consectetur adipisicing elit.
</div>
<div class="megamenu" data-id="menu-item-138">
Danushka Megamenu... Add data id for mapping
</div>

JS loop to add event listeners not working during one condition for second element

I am working on a piece of code to toggle the visibility of some UL items by clicking corresponding buttons by toggling a class on the UL that changes opacity/height to 0 (so that I can also apply transitions). The second element doesn't work when the first is toggled to be invisible. The onclick event does not register.
The code works when the button and h3 are not styled to appear on the same line, and breaks when I try to use flex, float, or inline to position the two elements side by side. Is there a method that I can use to position them as such and still retain full functionality?
const buttons = document.getElementsByClassName("toggle");
const lists = document.getElementsByClassName("list");
for (let i = 0; i < buttons.length; i++) {
buttons[i].addEventListener('click', function() {
toggle(i);
})
};
function toggle(i) {
if (lists[i].classList.contains("hide")) {
lists[i].classList.remove("hide");
} else {
lists[i].classList.add("hide");
}
}
<div id="sidebar">
<div class="side">
<div class="header">
<h3>Protein</h3>
<button class="toggle"></button>
</div>
<div>
<ul class="list">
<li class="fi">Beef</li>
<li class="fi">Fish</li>
<li class="fi">Lamb</li>
<li class="fi">Pork</li>
<li class="fi">Poultry</li>
<li class="fi">Shellfish</li>
<li class="fi">Vegetarian</li>
</ul>
</div>
</div>
<div class="side">
<div class="header">
<h3>Cuisine</h3>
<button class="toggle"></button>
</div>
<ul class="list">
<li class="fi">African</li>
<li class="fi">American</li>
<li class="fi">Asian</li>
<li class="fi">British</li>
<li class="fi">Cajun Creole</li>
<li class="fi">Carribean</li>
<li class="fi">Eastern European</li>
<li class="fi">Show More</li>
</ul>
</div>
</div>
<style>
.header{
display: flex;
align-items: center;
}
.hide {
height: 0;
opacity: 0;
margin: 0;
}
</style>
gif of the issue

As the response for user120242 says you are overlaying the below side class div you can resolve it by adding your <div class="side"> element a overflow: hidden; style to avoid overflowing the below div, so try this:
If you want to place elements next to each other you need working with flexbox as #user120242 said.
const buttons = document.getElementsByClassName("toggle");
const lists = document.getElementsByClassName("list");
for (let i = 0; i < buttons.length; i++) {
buttons[i].addEventListener('click', function() {
toggle(i);
})
};
function toggle(i) {
if (lists[i].classList.contains("hide")) {
lists[i].classList.remove("hide");
} else {
lists[i].classList.add("hide");
}
}
.side {
overflow: hidden;
}
<div id="sidebar">
<div class="side">
<div class="header">
<h3>Protein</h3>
<button class="toggle"></button>
</div>
<div>
<ul class="list">
<li class="fi">Beef</li>
<li class="fi">Fish</li>
<li class="fi">Lamb</li>
<li class="fi">Pork</li>
<li class="fi">Poultry</li>
<li class="fi">Shellfish</li>
<li class="fi">Vegetarian</li>
</ul>
</div>
</div>
<div class="side">
<div class="header">
<h3>Cuisine</h3>
<button class="toggle"></button>
</div>
<ul class="list">
<li class="fi">African</li>
<li class="fi">American</li>
<li class="fi">Asian</li>
<li class="fi">British</li>
<li class="fi">Cajun Creole</li>
<li class="fi">Carribean</li>
<li class="fi">Eastern European</li>
<li class="fi">Show More</li>
</ul>
</div>
</div>
<style>
.header{
display: flex;
align-items: center;
}
.hide {
height: 0;
opacity: 0;
margin: 0;
}
</style>

I've added pointer-events: none so it doesn't intercept mouse events and it works, but you should probably find another way to deal with it. I don't know what you're doing for animations, code, nor the rest of the styling, so this might be the best solution depending on what you're doing.
I've added a "Show Problem" button to show what's happening. The list is (repainted in a new stacking context triggered by opacity) and covering the second list.
Another solution is to set the position style. So adding position: relative to the .hide { position: relative } will also work
Scroll to bottom to read a detailed description of the cause (opacity style).
// show problem
test.onclick=()=>{
if (lists[0].classList.contains("hide1")) {
lists[0].classList.remove("hide1");
} else {
lists[0].classList.add("hide1");
}
}
const buttons = document.getElementsByClassName("toggle");
const lists = document.getElementsByClassName("list");
for (let i = 0; i < buttons.length; i++) {
buttons[i].addEventListener('click', function() {
toggle(i);
})
};
function toggle(i) {
if (lists[i].classList.contains("hide")) {
lists[i].classList.remove("hide");
} else {
lists[i].classList.add("hide");
}
}
.header { display:flex; flex-direction:row }
.header{
display: flex;
align-items: center;
}
.hide {
height: 0;
opacity: 0;
margin: 0;
pointer-events: none /* don't intercept mouse events */
}
/* show problem */
.hide1 {
height: 0;
margin: 0;
opacity: 0.5;
border: 1px solid red;
}
.hide1 * {
border: 1px solid blue;
}
<button id="test">Show Problem</button>
<div id="sidebar">
<div class="side">
<div class="header">
<h3>Protein</h3>
<button class="toggle"></button>
</div>
<div>
<ul class="list">
<li class="fi">Beef</li>
<li class="fi">Fish</li>
<li class="fi">Lamb</li>
<li class="fi">Pork</li>
<li class="fi">Poultry</li>
<li class="fi">Shellfish</li>
<li class="fi">Vegetarian</li>
</ul>
</div>
</div>
<div class="side">
<div class="header">
<h3>Cuisine</h3>
<button class="toggle"></button>
</div>
<ul class="list">
<li class="fi">African</li>
<li class="fi">American</li>
<li class="fi">Asian</li>
<li class="fi">British</li>
<li class="fi">Cajun Creole</li>
<li class="fi">Carribean</li>
<li class="fi">Eastern European</li>
<li class="fi">Show More</li>
</ul>
</div>
</div>
<style>
.header{
display: flex;
align-items: center;
}
.hide {
height: 0;
opacity: 0;
margin: 0;
pointer-events: none
}
</style>
The problem is related to the z-index stacking context being triggered by the opacity style due to re-render: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Positioning/Understanding_z_index/The_stacking_context
You can prove this by setting opacity: 0.9 on the second list's header, so that the second list's header renders in the same context layer, and see that you will then be able to click the button.
This SO answer summarizes it well:
What has bigger priority: opacity or z-index in browsers?
If an element with opacity less than 1 is not positioned, implementations must paint the layer it creates, within its parent stacking context, at the same stacking order that would be used if it were a positioned element with ‘z-index: 0’ and ‘opacity: 1’

jquery dynamic filter list

I'm trying to make a filter list on keypress. For example if I write in input "It", the elements that doesn't match this input value are hidden. I'm not sure if the idea I have with code below does the job. Any tips will be highly appreciated!
$('ul li ul li').addClass('displayNone');
var geInputValue = $('input').val();
var getInputLength = $('input').length;
function sortDynamically(){
$('input').on('keypress', function(){
for(var i=0; i < getInputLength; i++){
if(getInputValue === $('li').text){
// remove everything that doesnt match input value
$('li').siblings().addClass('displayNone');
}
else{
$('li').siblings().removeClass('displayNone');
});
}
sortDynamically();
ul, li{
list-style-type: none;
margin: 0;
padding: 0;
}
.displayNone{
display: none;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" />
<ul class="list">
<li>Item</li>
<li>Product
<ul>
<li>Bike</li>
</ul>
</li>
<li>About</li>
</ul>

This code filters based on what you type. If there is nothing in the text input then everything is shown.
$('input').on('keypress keyup', function(){
var value = $(this).val().toLowerCase();
if (value != '') {
$('.list > li').each(function () {
if ($(this).text().toLowerCase().indexOf(value) > -1) {
$(this).removeClass('displayNone');
} else {
$(this).addClass('displayNone');
}
});
} else {
$('.list > li').removeClass('displayNone');
}
});
ul, li{
list-style-type: none;
margin: 0;
padding: 0;
}
.displayNone{
display: none;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" />
<ul class="list">
<li>Item</li>
<li>Product
<ul>
<li>Bike</li>
</ul>
</li>
<li>About</li>
</ul>

jQuery provides filters and javascript implements toLowerCase() and includes() methods that you can use to improve your code
<body>
<style>
.displayNone
{
display: none;
}
</style>
<input type="text" id="input-filter"/>
<ul class="list">
<li>Item</li>
<li>Product
<ul>
<li>Bike</li>
</ul>
</li>
<li>About</li>
</ul>
<script>
var items = $('ul.list li');
$('#input-filter').on('input', function ($event)
{
items.addClass('displayNone').filter(function (item)
{
return $(this).text().toLowerCase().includes($($event.target).val().toLowerCase());
}).removeClass('displayNone');
});
</script>
</body>

Change background color on anchor in listitem when clicked

I have menu constructed by ul li with anchor tags in each. Css is applied to the anchor
and anchor:hover however I want the selected item to show that it is selected be changing the background a different color. anchor:active does not work.
I am trying javascript but not yet successful. Can this be soley done through css? I have looked at so many examples, but none actually worked right.
JAVASCRIPT
<script type="text/javascript">
function ChangeColor(obj) {
var li = document.getElementById(obj.id);
li.style.background = "#bfcbd6";
}
</script>
HTML
<div id="navigation">
<ul>
<li><a onclick="changecolor(this);" href="Default.aspx">Home</a></li>
<li><a onclick="changecolor(this);" href="View.aspx">View</a></li>
<li><a onclick="changecolor(this);" href="About.aspx">About</a></li>
</ul>
</div>
CSS - Simplified
#navigation ul {
list-style-type: none;
}
#navigation li
{
float: left;
}
#navigation a
{
background-color: #465c71;
}
#navigation a:hover
{
background-color: #bfcbd6;
}

you don't need to get id again for handling element. obj references the actual element.
<script type="text/javascript">
function ChangeColor(obj) {
obj.style.backgroundColor = "#bfcbd6";
}
</script>
Edit: And javaScript is case sensitive, so you should check your function names.
Here is a jsFiddle Demo

I have found a way to use JavaScript to solve this situation. This works for having MasterPage. Changing the id of the selected tab will then reference the css for that
selected tab only while setting the other tabs id's to null.
HTML
<div id="navbar">
<div id="holder">
<ul id="menulist">
<li><a onclick="SelectedTab(this);" href="#" id="onlink" >Home</a></li>
<li><a onclick="SelectedTab(this);" href="#" id="" >Products</a></li>
<li><a onclick="SelectedTab(this);" href="#" id="">Services</a></li>
<li><a onclick="SelectedTab(this);" href="#" id="">Gallery</a></li>
<li><a onclick="SelectedTab(this);" href="#" id="" >Contact</a></li>
</ul>
</div>
</div>
JavaScript
function SelectedTab(sender) {
var aElements = sender.parentNode.parentNode.getElementsByTagName("a");
var aElementsLength = aElements.length;
var index;
for (var i = 0; i < aElementsLength; i++)
{
if (aElements[i] == sender) //this condition is never true
{
index = i;
aElements[i].id="onlink"
} else {
aElements[i].id=""
}
}
}
Css for changing the background color after tab has been selected
#holder ul li a#onlink
{
background: #FFF;
color: #000;
border-bottom: 1px solid #FFF;
}