Develop Reference

Is the child element visible in the parent

I am making a comment system, there is a certain block in which there are others (messages) how, when scrolling through these messages, to find out whether the user sees one particular one (for example, with the identifier x) or not,
HTML:
<div class="parent">
<div class="msg" id="a"></div>
<div class="msg" id="b"></div>
<div class="msg" id="c"></div>
<div class="msg" id="x"></div>
</div>
CSS:
.parent {
width: 100%;
height: 100%;
height: 89%;
overflow: scroll;
padding-top: 10px;
padding-bottom: 70px;
}
.msg {
width: 98%;
height: 500px;
padding: 10px;
position: relative;
margin: 0 auto;
border: 2px hsl(174deg 72% 41%) solid;
color: hsl(174deg 72% 41%);
border-radius: 20px
px
;
margin-top: 10px;
}
JS:
document.querySelector(".parent").onscroll = () => {
//what to write here?
}
That is: if the message has become visible in the general block, then paint it in yellow
I tried different options: getComputedStyle, and getBoundingClientRect, and offset, but none of this helped me, they constantly say that the message is visible
BUT:
getBoundingClientRect doesn't work, I don't need to check if it's visible in the whole window, I need to check if it's ONLY visible in a div element
WHEN SCROLLING A PARENT ELEMENT

As suggested in the comments by other user, what you are looking for is the Intersection Observer API
https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
Here's a demo trying to apply the concept to your scenario. It's not very well factored but clearly shows a document containing both your .msg container (.parent) styled as overflow-y: scroll; and other elements before and after taking space on the viewport.
All .msg elements will be observed for intersection in the visible space of their parent so that every time each one of them will be visible, its id will be printed on console. Plus there's an added trigger callback that will be invoked in the event described above, that will check for a condition (for example if the element currently became visible has id == 'c') to perform an action.
//this will be called everytime a target element being observer became visible,
//and will check a condition before performing an action (if the element.id === c for example)
const trigger = (element)=>{
if (element.id === 'c')
console.log('condition met! element with id == c was reached.');
}
const observerOptions = {
root: null,
rootMargin: '0px',
threshold: 0
};
//gets called everytime any of the targets appears on the viewport
const observerCallback = (entries, observer) => {
//for each of the observed entries
entries.forEach(entry => {
//console logs the element id currently intersecting the viewport
if (entry.isIntersecting){
console.log(entry.target.id);
trigger(entry.target);
}
});
};
//sets up an observer...
//calling the observerCallback when the observed targets will be intersecting the viewport
const observer = new IntersectionObserver(observerCallback, observerOptions);
//the targets the observer will be observing for (each .msg children inside the .parent element)
const observerTargets = document.querySelectorAll('.parent > .msg');
observerTargets.forEach(target => observer.observe(target));
.other-content{
display: block;
outline: dashed 3px gray;
height: 100px;
display: flex;
align-items: center;
justify-content: center;
font-family: arial;
color: gray;
}
.parent {
display: block;
margin: 10px 10px;
height: 120px;
overflow-y: scroll;
outline: solid 1px gray;
}
.msg {
position: relative;
display: block;
width: 100%;
height: 200px;
padding: 0;
margin: 10px 0;
box-sizing: border-box;
border: solid 2px hsl(174deg 72% 41%);
border-radius: 10px;
}
.msg::before {
position: absolute;
content: 'id: ' attr(id);
top: 50%;
left: 50%;
border-radius: 1rem;
padding: 1rem 1rem;
background: gray;
font-size: 2rem;
font-weight: 600;
color: white;
}
<div class="other-content">
before..
</div>
<div class="parent">
<div class="msg" id="a"></div>
<div class="msg" id="b"></div>
<div class="msg" id="c"></div>
<div class="msg" id="x"></div>
</div>
<div class="other-content">
..after
</div>

Modal stops working after image changes on page

Im building an app where you can like and dislike movies. I have a database of movies and show each one to the user. When you click like or dislike it takes you to the next poster.
I also have access to the description and rating. I've added my own modal to show the user when clicked more information on that movie.
The problem Im having is the modal works for the first movie and changes the class to active. However on the second one it stops working. I can see in the inspector the modal code is there and has the correct information for that movie. But the modal seems to still not work/become unresponsive. Perhaps its an error that I've missed. I notice that it does add active once again on the first item. Perhaps I need to find a way to switch to the current movie instead or incorporate the modal into the slides more? or find a way to reset it..
EDIT -:
Adding to the above. Having done a bit more testing. It seems like the modal doesnt know what id the slide is on.. So it never knows when the slide is changed.. Any ideas how I would do this?
EDIT2 -:
I've now got it so every modal has a unique id per poster using the contact.id. Any way to link the modal id together with the slides so when I change the slide the modal knows and changes to active on the next slide?
const modalBtn = document.querySelectorAll(".modal-btn");
const modalBg = document.querySelectorAll("movie-modal");
const modalClose = document.querySelectorAll(".close-button");
const overlay = document.querySelectorAll("overlay");
const overlayClose = document.querySelectorAll("overlay");
const activeModal = document.querySelectorAll(".movie-modal:first-child")
modalBtn.forEach(function(btn, index){
btn.addEventListener('click', function(click) {
console.log(click)
modalBg.classList.add('active');
overlay.classList.add('active');
var content_id = activeModal.data("id");
console.log(content_id)
});
});
modalClose.forEach(function(btn, index){
btn.addEventListener('click', function(click) {
console.log(click)
modalBg.classList.remove('active');
overlay.classList.remove('active');
});
});
overlay.forEach(function(overlay, index){
overlay.addEventListener('click', function() {
overlayClose.classList.remove('active');
});
});
overlay.forEach(function(overlay, index){
overlay.addEventListener('click', function() {
const modals = document.querySelectorAll('.movie-modal.active')
modals.forEach(modal => {
modal.classList.remove('active');
overlay.classList.remove('active');
})
})
});
$(function(){
var $activeSlide = $('#slides .slide:first-child');
// show first slide
$activeSlide.addClass("active");
// on click event decline
$("#decline").on("click", function(){
goToSlide('decline');
});
// on click approve then what?
$("#approve").on("click", function(){
var content_id = $activeSlide.data("id");
console.log(content_id)
goToSlide('approve');
// $.ajax({
// url: "/user_contents/liked" + content_id,
// method: "post",
// dataType: "ajax"
// });
});
// adding the 'showing' or 'active' slide class to each element
function goToSlide(action) {
$activeSlide.removeClass("active");
$activeSlide = $activeSlide.next(".slide");
// send data to controller
if(action == "approve"){
console.log(action);
} else {
console.log('dislike');
}
$activeSlide.addClass("active");
}
});
.movie-modal {
position: fixed;
top: 50%;
left: 50%;
transform: translate(-50%, -50%) scale(0);
transition: 200ms ease-in-out;
box-shadow: rgba(0, 0, 0, 0.35) 0px 5px 15px;
border-radius: 10px;
z-index: 10;
background-color: white;
width: 300px;
max-width: 80%;
color: black;
}
.movie-modal.active{
transform: translate(-50%, -50%) scale(1);
}
.movie-modal-header {
padding: 8px 16px;
display: flex;
justify-content: space-between;
align-items: center;
border-bottom: 1px solid rgb(182, 182, 182);
}
.movie-rating {
font-size: 1.25rem;
font-weight: bold;
}
.close-button {
cursor: pointer;
border: none;
outline: none;
background: none;
font-size: 1.25rem;
font-weight: bold;
}
.movie-modal-body {
padding: 16px;
color: rgb(160, 160, 160);
}
#overlay {
position: fixed;
opacity: 0;
top: 0;
left: 0;
right: 0;
bottom: 0;
background-color: rgba(0, 0, 0, 0.35);
pointer-events: none;
transition: 200ms ease-in-out;
}
#overlay.active {
opacity: 1;
pointer-events: all;
}
#slides {
position: relative;
height: 100%;
padding: 0px;
margin: 0 auto;
list-style-type: none;
}
.slide {
position: absolute;
left: 0px;
top: 0px;
width: 100%;
height: 100%;
opacity: 0;
z-index: 1;
box-sizing: border-box;
color: #fff;
-webkit-transition: opacity 1s;
-moz-transition: opacity 1s;
-o-transition: opacity 1s;
transition: opacity 1s;
}
.showing {
opacity: 1;
z-index: 2;
}
#slide-controls {
margin: 20px 0 400px;
width: 100%;
position: absolute;
display: flex;
justify-content: center;
justify-content: space-between;
z-index: 10;
color: #ffffffba;
font-size: 24px;
top: 50%;
}
.image-carousel {
width: 100%;
height: 642px;
margin: 0 auto;
background-size: contain;
background-repeat: no-repeat;
position: relative;
}
#decline {
margin-left: 16px;
}
#approve {
margin-right: 16px;
}
.img-thumbnail {
padding: 0 !important;
}
<ul id="slides">
<% #contents.each_with_index do |content, i| %>
<li class="slide <%= 'active' if i == 0 %>" data-id="<%= content.id %>">
<div class="image-carousel" style="background-image: url('<%= content.poster %>')">
</div>
<button class="modal-btn">Open Modal</button>
<div id="movie-modal <%= content.id %>" class="movie-modal">
<div class="movie-modal-header">
<div class="movie-rating" style="">Average rating: <strong><%= content.rating %></strong></div>
<button class="close-button">×</button>
</div>
<div class="movie-modal-body"><p><%= content.description %></p></div>
</div>
<div id="overlay <%= content.id %>"></div>
</li>
<% end %>
</ul>
<div id="slide-controls">
<span id="decline"><i class="fa fa-solid fa-thumbs-down fa-2x"></i></span>
<span id="approve"><i class="fa fa-solid fa-thumbs-up fa-2x"></i></span>
</div>
This shows when the first poster is clicked the modal works and movie-modal active is added to the modal class
The second image with Morbius in it.. The modal class doesnt change for the current slide showing however it changes for the previous slide.. BUT the previous slide only changes once and then sticks to active. Nothing is shown on the poster.

How can I keep onClickOutside() method disabled until I use onClick()?

When I click on my element with an event listener I supposed to get my popup shown, which works just fine until I introduce onClickOutside(). Using ng-click-outside
export class Component {
private isPopupDisplayed: boolean = false;
onClick() {
console.log('Clicked');
this.isPopupDisplayed = true;
}
onClickedOutside(event) {
this.isPopupDisplayed = false;
}
}
.popup{
position: absolute;
z-index: 3;
width: 200px;
height: 94px;
background-color: $secondary-color;
left: 0%;
bottom: 0%;
padding: 15px 0px;
margin: 12px;
border: 1px solid $modal-border-color;
border-radius: 4px;
box-shadow: 0px 2px 6px rgba(0, 0, 0, 0.25);
li:hover {
background-color: $accent-color;
}
li {
padding-top: 5px;
height: 32px;
}
}
<div *ngIf="isPopupDisplayed" >
<ul class="popup" (clickOutside)="onClickedOutside($event)">
<li><a>My Details</a></li>
<li><a>Sign out</a></li>
</ul>
</div>
<div class="presenter-menu_avatar" (click)="onClick()" >
<img [src]="avatarUrl">
</div>
When I am trying to introduce onClickOutside() method, I can see that both methods are triggered at the same time as my popup still not there and that automatically triggers not even showing it up.
My aim is to simply show the popup when onClick() and hide it when clicked outside of it.

Add stopPropagation event in click function
onClick(event) {
event.stopPropagation()
console.log('Clicked');
this.isPopupDisplayed = true;
}
<div class="presenter-menu_avatar" (click)="onClick($event)" >
<img [src]="avatarUrl">
</div>

Assign a value to input field

let slider = document.getElementById("slider");
let rightBtn = document.getElementById("rightbutton");
let leftBtn = document.getElementById("leftbutton");
let element = document.getElementById("elementtype").innerHTML;
let celciusBoiling = document.getElementById("celciusboiling").value;
let chlorine = ["Chlorine", 100, 200];
function moveSliderRight() {
if (rightBtn.onclick) {
slider.value++;
}
}
function moveSliderLeft() {
if (leftBtn.onclick) {
slider.value--;
}
}
function main() {
moveSliderRight();
moveSliderLeft();
if (slider.value == parseInt(2)) {
element = chlorine[0];
celciusBoiling = chlorine[1];
}
}
main();
* {
margin: 0;
padding: 0;
box-sizing: border-box;
background-color: peachpuff;
}
header {
width: 90%;
margin: 10px auto 0px;
}
header h1 {
text-align: center;
border: 1px solid black;
padding: 15px 0px;
}
.navbar {
width: 75%;
margin: 50px auto 50px;
padding: 10px 0px;
display: flex;
justify-content: space-around;
border: 1px solid black;
}
.navlinks {
border-right: 1px solid black;
width: 50%;
text-align: center;
display: block;
}
#nav3 {
border: none;
}
#intro {
margin: 0px auto 50px;
width: 40%;
text-align: center;
}
#slider {
-webkit-appearance: none;
background-color: grey;
width: 90%;
display: block;
margin: auto;
}
#slider::-webkit-slider-thumb {
cursor: pointer;
}
#slider::-moz-range-thumb {
cursor: pointer;
}
#valuetag {
text-align: center;
margin-top:25px;
}
h2 {
text-align: center;
font-size: 45px;
text-decoration: underline;
}
#display {
width: 90%;
margin-left: 50px;
margin-bottom: 50px;
font-size: 40px;
}
#display div {
display: inline-block;
width: 45%;
text-align: center;
}
span {
font-size: 15px;
}
.boiling {
margin-left: 6%;
}
.boilingpointslider {
text-align: center;
}
button {
margin: 20px 20px 20px 0px;
width: 75px;
}
<header>
<h1>Periodic Table Gases - Interative Slider</h1>
<nav>
<div class="navbar">
<div class="navlinks">Boiling Point</div>
<div class="navlinks" id="nav3">Melting Point</div>
</div>
</nav>
</header>
<div id="intro">
<p>Interact with the slider buttons to view the displayed properties held by gases, within the periodic table of elements.</p>
</div>
<h2 id="elementtype">Hydrogen</h2>
<div id="display">
<div class="boiling">
<h2>Boiling Point</h2>
<input id="celciusboiling" type="number" value="0"><span>℃</span>
<input id="fahrenboiling" type="number"><span>℉</span>
<input id="kelvinboiling" type="number"><span>K</span>
</div>
<div class="melting">
<h2>Melting Point</h2>
<input id="celciusmelting" type="number"><span>℃</span>
<input id="fahrenmelting" type="number"><span>℉</span>
<input id="kelvinmelting" type="number"><span>K</span>
</div>
</div>
<input type="range" min="0" max="9" value="0" id="slider">
<div class="boilingpointslider">
<button id="leftbutton" onclick="moveSliderLeft()">Left</button>
<button id="rightbutton" onclick="moveSliderRight()">Right</button>
</div>
I am having issues transferring a value to an input field.
Within the snippet linked their is a heading with the value hydrogen and to the bottom left their is a boiling point heading with a input field for celcius.
I'm trying to achieve a scenario whereby you move the slider along using the buttons and at each value the heading changes to a different element and the input value for just the celcius boiling point changes.
I can't get this to work though. The buttons are working to make the slider move left and right, but for whatever reason i cant get the value to appear within the input field or change the heading. I've displayed the code i have already to get the buttons to move the slider and a snippet of what i thought would allow the changes i want to take place when the slider value changes to 2. I cant get it to to work though
Thanks.

You don't show your HTML, but I presume that slider is an input (text or hidden).
The value attribute is a string, even if you assign it a number, so you need to first convert it to a integer if you want to increment or decrement it, like so:
slider.value = parseInt(slider.value)++ // or --
Note that also you are trying to parseInt(2) down in your main(), which makes no sense as 2 is already an integer.

How to add dynamic listener and get value of target

I've created a custom dropdown and would like to get the text content of the clicked element within.
Dropdown elements are created dynamically as are the event listeners but the listeners seem not to be working correctly.
Dropdown example:
I can see the listeners on each div within the dev tools.
Event listener of child div:
The first div in the dropdown fills the input with it's value but the others do not.
(function() {
let departments = ['Accounting', 'Human Resources', 'IT', 'Warehouse'];
let element = document.getElementById('dd-Department');
departments.forEach(v => {
let div = document.createElement('div');
div.appendChild(document.createTextNode(v));
div.addEventListener('click', () => {
element.parentNode.querySelector('input').value = v;
});
element.appendChild(div);
});
})();
.form-question {
display: flex;
flex-direction: column;
justify-content: center;
margin: 0 0 3rem;
min-height: 3rem;
}
.form-question__title {
color: #342357;
font-size: 1.5rem;
padding: 1rem;
}
.input-container {
border-bottom: solid 2px #333333;
position: relative;
}
input[readonly] {
cursor: pointer;
}
.input-container input {
border: none;
box-sizing: border-box;
outline: 0;
padding: .75rem;
position: relative;
width: 100%;
}
.input-container:focus-within .dropdown {
transform: scaleY(1);
}
.dropdown {
background: #ffffff;
box-shadow: 0 5px 12px #333333;
left: 0;
max-height: 300px;
overflow-y: auto;
padding: 0;
position: absolute;
right: 0;
top: calc(100% + 2px);
transform: scaleY(0);
transform-origin: top;
transition: transform .3s;
z-index: 10;
}
.dropdown div {
border-bottom: 2px solid #777777;
cursor: pointer;
padding: 8px;
z-index: 20;
}
.dropdown div:hover {
background: #dddddd;
font-weight: 800;
}
<div class="form-question">
<div class="form-question__title">
<span>Department</span>
</div>
<div class="form-question--dropdown input-container">
<input type="text" name="Department" readonly="readonly"></input>
<div id="dd-Department" class="dropdown"></div>
</div>
</div>
I also took a stab at event delegation, but could not get the text content of the clicked div. The target is the parent of the intended div, thus the text content was all child values combined.
let element = document.getElementById('dd-Department');
element.addEventListener('click', e => {
if (e.target && e.target.classList.contains('dropdown')) {
e.target.parentNode.parentNode.querySelector('input').value = e.target.textContent;
}
}, true);
Event Delegation on click of child div:
Am I missing something here?
UPDATE
Thank you #dawn for pointing out css as the problem.
I've worked around this by changing
.input-container:focus-within .dropdown
to
.input-container.active .dropdown
and adding the active class with javascript.
document.querySelectorAll('.input-container').forEach(v => {
v.onclick = () => v.classList.toggle('active');
});
Issue now is that on click of anything other than the input-container the dropdown is still active.
The following works but feels like a hack.
document.querySelectorAll('.input-container').forEach(v => {
v.addEventListener('focus', () => v.classList.add('active'), true);
v.addEventListener('blur', () => setTimeout(() => v.classList.remove('active'), 75), true);
});
Are there more elegant solutions?

This situation is a problem with css,When you click on the div,The first thing that triggers is "transform: scaleY(0)" and the ".dropdown" has invisible,so Cannot trigger click event.
Don't use input:focus-within to control the Visibilityof the drop-down box, because when you click the drop-down box, the input has lost focus.