Develop Reference

Add class to a div if another div has a class

I did a lot of searching and read dozens of questions and answers on this topic and wrote the following code but it won't work for some reason. I'm looking for help troubleshooting this.
This is what I want to happen:
When the user hovers over a menu item, a dropdown appears.
Then the entire header (currently has the ID #header) gets a new class (.header-new-class)
I found that when they hover over a menu item (li), the site automatically adds the class "open" to the menu item (the menu item already has the class .menu-item)
So my logic is, when the menu item has the class "open", it adds the class "header-new-class" to the div with the ID #header
This is a very cleaned up version of the HTML:
<div ID="header">
<div>
<div>
<div>
<div>
<div>
<nav>
<nav>
<div>
<div>
<ul>
<li class="menu-item open">
</li>
</ul>
</div>
</div>
</nav>
</nav>
</div>
</div>
</div>
</div>
</div>
</div>
This is the code I wrote:
$(document).ready(function(jQuery) {
if ($('.menu-item').hasClass('open')) {
$('#header').addClass('header-new-class');
}
});
It's not working. What am I doing wrong?
Thanks in advance.

if you want to add a class on the header when the mouse is on the menu item, do it like this,
if you also want to remove the class then use the commented code below.
if you have questions, feel free to ask
$(document).ready(function(){
$('.menu-item').on('mouseover',function(){
/*$('.menu-item').removeClass('open');
$(this).addClass("open");*/
if($(this).hasClass('open')){
$('#header').addClass('yourNewClass');
}else{
$('#header').removeClass('yourNewClass');
}
});
/*$('.menu-item').on('mouseleave',function(){
$('.menu-item').removeClass('open');
$('#header').removeClass('yourNewClass');
});*/
});
.yourNewClass .menu-item.open {color: red;}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div ID="header">
<div>
<div>
<div>
<div>
<div>
<nav>
<nav>
<div>
<div>
<ul>
<li class="menu-item open">
item 1
</li>
<li class="menu-item">
item 2
</li>
<li class="menu-item">
item 3
</li>
</ul>
</div>
</div>
</nav>
</nav>
</div>
</div>
</div>
</div>
</div>
</div>

You can use same event many times. So, this is achievable with normal .hover.
$(document).ready(function(){
$('.menu-item').hover(function(){
$('#header').addClass('header-new-class');
},function(){
/* function to remove class when hovering is over */
})
If you absolutely need to check if the class open is present you can do it inside the hover function.
You can also use mouseenter and mouseleave
$(document).on({
mouseenter: function () {
//stuff to do on mouse enter
},
mouseleave: function () {
//stuff to do on mouse leave
}
}, ".selector");

Why you are set class for hover via jquery. CSS have functionality of :hover which give the same effect that you want.
#header:hover{
background-color : lightBlue;
}
.menu-item:hover{
color: blue;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div ID="header">
<div>
<div>
<div>
<div>
<div>
<nav>
<nav>
<div>
<div>
<ul>
<li class="menu-item">
Sample Link 1
</li>
<li class="menu-item">
Sample Link 2
</li>
<li class="menu-item">
Sample Link 3
</li>
</ul>
</div>
</div>
</nav>
</nav>
</div>
</div>
</div>
</div>
</div>
</div>

If handlebars list is empty, show a message

I am using handlebars to show data. I have a ul that filters the data and populates another ul. The filter ul has a couple of choices that currently output an empty ul. I want the empty ul to show a message that says "There are no sessions yet."
I am trying to use handlebars if helper. The problem I am running into is the message is showing up in all ul, even if it is not empty.
<div class="session-details-inner">
<div class="sidebar left-sidebar left-align">
<ul id="session_filter_15308050681959955093" class="session_filters no-list-style">
<li>
<a class="themelink active" data-filter="All" title="All Tracks">General</a>
</li>
<li>
<a class="themelink" data-filter="Destination Marketers" title="Destination Marketers">Destination Marketers</a>
</li>
<li>
<a class="themelink" data-filter="Exhibitions" title="Exhibitions">Exhibitions</a>
</li>
<li>
<a class="themelink" data-filter="Financials" title="Financials">Financials</a>
</li>
<li>
<a class="themelink" data-filter="Registration" title="Registration">Registration</a>
</li>
<li>
<a class="themelink" data-filter="Technical" title="Technical">Technical</a>
</li>
<li>
<a class="themelink" data-filter="Venues" title="Venues">Venues</a>
</li>
</ul>
</div>
<div class="sidebar right-sidebar left-align">
<ul class="scheduleday_wrapper themeborder no-list-style">
{{#each ./Sessions}}
{{#if TrackDescription.length}}
<li class="themeborder individual-session accordion-panel" data-track="{{TrackDescription}}">
<div class="session_content_wrapper expandable accordion">
<div class="session_content ">
<div class="session_title">
<h6>{{Title}}</h6>
</div>
</div>
</div>
<div class="session_content_extend hide session_content_wrapper panel">
<div class="session_content ">
<div class="session_excerpt">{{SessionDetails}}</div>
<div class="session_title_list">
<span class="ti-bookmark"></span>
<div class="session_title_item">{{TrackDescription}}</div>
</div>
</div>
</div>
</li>
{{else}}
<li class="no-sessions">There are no session yet.</li>
{{/if}}
{{/each}}
</ul>
</div>
<script type='text/javascript'>
$(document).ready(function($) {
$('.accordion').on('click', function() {
$parent_box = $(this).closest('.accordion-panel');
//$parent_box.siblings().find('.panel').slideUp(500);
$parent_box.siblings().find('.icon').removeClass('down');
$parent_box.find('.panel').slideToggle(500);
$parent_box.find('.icon').toggleClass('down');
});
$('ul.scheduleday_wrapper li .session_content_wrapper').on('click', function(ev) {
    ev.preventDefault();
    jQuery(this).next().toggleClass('hide');
});
$(".session_filters a").click(function(){
jQuery(".session_filters a").removeClass("active");
jQuery(this).addClass("active");
currentSessionType=jQuery(this).attr("data-filter");
jQuery(".individual-session").hide();
jQuery(".individual-session[data-track='"+currentSessionType+"'").show();
individualSession = jQuery('.individual-session');
if(currentSessionType == 'All'){
jQuery(".individual-session").show();
}
});
});
</script>

If you want to check & conditionally render if there are no sessions, shouldn't you do the length check on your Sessions instead of the TrackDescription?

Added this snippet of jQuery to check if all li had a style of display: none. If all li have display: none, show message li else hide message li.
if($('.scheduleday_wrapper').children(':visible').length == 0){
jQuery(".no-sessions").show();
}
else{
jQuery(".no-sessions").hide();
}

How to hide and show elements based on current hovered element?

We need to be able to hide and show elements based on currently hovered element. We have tried the following below, but it does not add the is-active class and remove it based on what other element is on hover.
How can we hide and show elements based on the current hovered element?
Goal (based on example below):
when you hover over some under first, display <div class="two" id="some-link">some link</div> using is-active class
when you hover over path under first, <div class="two" id="some-link">some linke</div> should not display (remove is-active class), and <div class="two" id="path-link">path link</div> should display (add is-active class)
Current issue:
is-active class is not being removed when on hover element is changed
$(function() {
$('li#two').hover( function() {
var el_two = $(this);
var el_id = el_two.attr('id');
var el_link = el_two.attr('data-at');
var el_sel = '#'+el_link+'.'+ el_id;
var el_parent = el_two.parent().parent();
el_parent.find('.is-active').removeClass('is-active');
$(el_sel).addClass('is-active');
});
});
.two {
display: none;
}
.is-active {
display: block;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
<li id="one">
first
<div class="one">
<ul>
<li data-at="some-link" id="two">
some
</li>
<li data-at="path-link" id="two">
path
</li>
<li data-at="another-one" id="two">
another one
</li>
</ul>
<div class="dropdown">
<div class="two" id="some-link">some link text</div>
<div class="two" id="path-link">path link</div>
<div class="two" id="another-one">another one</div>
</div>
</div>
</li>
<li id="one">
second
<div class="one">
<ul>
<li>
another some
</li>
<li>
another path
</li>
</ul>
</div>
</li>
<li id="one">
third
<div class="one">
<ul>
<li>
third some
</li>
<li>
third path
</li>
</ul>
</div>
</li>
</ul>

First your .find() is using the wrong selector. You have find('is-active') which is an element name selector, you wanted a css class selector ie .is-active.
el_parent.find('.is-active').removeClass('is-active');
Note for removeClass() you don't use a css selector you just use a class name hence why you don't need the dot in that call
Now if you wanted to also have the class removed on hovering out of the element as well then you need to add an event listener for that, and call removeClass from there. .hover() uses a second argument for setting such an event listener callback.
$('li#two').hover(onHoverCallback,function(){
//code for finding the right element
$(el_sel).removeClass('is-active');
})
$(function() {
$('li#two').hover( function() {
var el_two = $(this);
var el_id = el_two.attr('id');
var el_link = el_two.attr('data-at');
var el_sel = '#'+el_link+'.'+ el_id;
var el_parent = el_two.parent().parent();
el_parent.find('.is-active').removeClass('is-active');
$(el_sel).addClass('is-active');
},function(){
var el_two = $(this);
var el_id = el_two.attr('id');
var el_link = el_two.attr('data-at');
var el_sel = '#'+el_link+'.'+ el_id;
$(el_sel).removeClass("is-active");
});
});
.two {
display: none;
}
.is-active {
display: block;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
<li id="one">
first
<div class="one">
<ul>
<li data-at="some-link" id="two">
some
</li>
<li data-at="path-link" id="two">
path
</li>
<li data-at="another-one" id="two">
another one
</li>
</ul>
<div class="dropdown">
<div class="two" id="some-link">some link text</div>
<div class="two" id="path-link">path link</div>
<div class="two" id="another-one">another one</div>
</div>
</div>
</li>
<li id="one">
second
<div class="one">
<ul>
<li>
another some
</li>
<li>
another path
</li>
</ul>
</div>
</li>
<li id="one">
third
<div class="one">
<ul>
<li>
third some
</li>
<li>
third path
</li>
</ul>
</div>
</li>
</ul>

Always one selected on list <li>

I have an input and users list. This input is a search box, so every time I type on the input it changes the users list reactively. How do I achieve that there's always one selected on the users list preferably the first list item then if I hover to other the selected changes and leaves to where I last hovered on. This is my html code:
<div class="user-container">
<input class="form-control user-search" placeholder="Search by name" type=“text">
<div id="userList">
<ul>
<li>
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
</ul>
</div>
</div>
This needs javascript, cause I wanted to know which is selected. So I can get its data. Also can use up and down keys in changing selection. Doesn't have to be a code that works. Maybe just help me with the logic and give me some pseudocode.

Try using css :hover , :not()
ul li:hover {
background: grey;
}
ul:hover li:first-child:not(:hover) {
background: transparent;
}
ul li:nth-of-type(1) {
background: grey;
}
<div class="user-container">
<input class="form-control user-search" placeholder="Search by name" type="text"/>
<div id="userList ">
<ul>
<li>
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
</ul>
</div>
</div>

another approach js wise would be...
create a css class
.selected{
/* css for selected class */
}
On page load, add this to first-child
$("some-first-child").addClass("selected")
on selecting any other class, remove it from above li and add it to new li class.
To setup a default, you can search for this class in html body
In case $('body').hasClass doesnt return true, you can always add it back toh the first li child.

Jquery search
$("input").on('input', function() {
var val = $(this).val().toUpperCase();
$("#userList li").each(function() {
if ($(this).text().trim().toUpperCase().indexOf(val) > -1) {
$(this).show();
} else {
$(this).hide();
}
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="user-container">
<input class="form-control user-search" placeholder="Search by name" type="text">
<div id="userList">
<ul>
<li>
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
</ul>
</div>
</div>

You want like this.
<style>
.active{
background: gray;
}
</style>
<script src="//code.jquery.com/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$("ul li").mouseover(function(){
$("ul li").removeClass("active");
$(this).addClass('active');
});
});
</script>
<div class="user-container">
<input class="form-control user-search" placeholder="Search by name" type=“text">
<div id="userList">
<ul style="width:100px;">
<li class="active">
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
<li>
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
<li>
Bob
</li>
<li>
Charlie
</li>
<li>
Foxtrot
</li>
</ul>
</div>
</div>
with up and down key working.. I am working on this wait.

override css of grandparent from child element

I have the following code structure:-
<li class="container">
<div class="wrap">
<div class="green">...</div>
</div>
</li>
<li class="container">
<div class="wrap">
<div class="xyz">...</div>
</div>
</li>
..
.. so on
Now li has the following css :-
margin-top:35px
I don't want to inherit the above margin for li which contains the class green but I want it for the class xyz.
I have tried using operator > in css but it doesn't work.

If you dont want margin-top:35px to be applied (inherit from parent li) to div.green then here is the solution
CSS
.green {
margin-top:-35px;
}
HTML
<li class="container">
<div class="wrap">
<div class="green">...</div>
</div>
</li>
<li class="container">
<div class="wrap">
<div class="xyz">...</div>
</div>
</li>

You can use :has() jQuery pseudo selector:
$('.container:has(.xyz)').css(...);

With this code structure, assuming a parent container:
<ul>
<li class="container">
<div class="wrap">
<div class="green">...</div>
</div>
</li>
<li class="container">
<div class="wrap">
<div class="xyz">...</div>
</div>
</li>
</ul>
You could do this:
ul li:nth-child(2) {
margin: 0;
}
https://developer.mozilla.org/en/docs/Web/CSS/:nth-child
But a rule to "If I have inside a div with xyz class then..." I think it is impossible in pure css.
I hope it helps.

There is no parent selector in css but you can use javascript:
$('.xyz').closest('.container').css('margin-top', '35px');