Develop Reference

How to put an element in hover state when scrolled down using javascript

I am trying to make a div element which when scrolled down will change properties drastically. Here is the codepen example of how I want it to work.
Instead of hover I want it so that when scrolled down, the page wide div will turn into that little circle div which when clicked will function as a back to the top button. It doesn't matter if more classes are added or anything of that sort. I am very new to js and I tried a few things and also googled about it, I got the scroll code from w3school's how to make a back to top button guide which specifies that when scrolled down by 20px the code would react, but I don't know how to turn the JavaScript to JS when scrolled down along with the transformation of the div.
Thanks in advance

I think you want to implement scroll to top functionality, very common these days in most of the web app.
You need to keep below things and design that feature.
There is one header, that should have a reference ID with hash to scroll back to top
Create a button that will always static position (JS) button, will show up when user scroll the window
Bind click event on the button that scroll back to top
Here is the you can see this implementation and use it.
.html
<h1 class="intro-copy">
Scroll down to use this simple back-to-top button made with modern vanilla javascript.
</h1>
<a class="top-link hide" href="" id="js-top">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 12 6"><path d="M12 6H0l6-6z"/></svg>
<span class="screen-reader-text">Back to top</span>
</a>
.css
body {
height: 2000px;
position: relative;
}
.intro-copy {
padding: 1em;
margin: 50vh auto;
max-width: 15em;
font-family: Helvetica;
font-weight: lighter;
font-size: 2em;
line-height: 1.2;
text-align: center;
}
.top-link {
transition: all .25s ease-in-out;
position: fixed;
bottom: 0;
right: 0;
display: inline-flex;
cursor: pointer;
align-items: center;
justify-content: center;
margin: 0 3em 3em 0;
border-radius: 50%;
padding: .25em;
width: 80px;
height: 80px;
background-color: #F8F8F8;
&.show {
visibility: visible;
opacity: 1;
}
&.hide {
visibility: hidden;
opacity: 0;
}
svg {
fill: #000;
width: 24px;
height: 12px;
}
&:hover {
background-color: #E8E8E8;
svg {
fill: #000000;
}
}
}
// Text meant only for screen readers.
.screen-reader-text {
position: absolute;
clip-path: inset(50%);
margin: -1px;
border: 0;
padding: 0;
width: 1px;
height: 1px;
overflow: hidden;
word-wrap: normal !important;
clip: rect(1px, 1px, 1px, 1px);
&:focus {
display: block;
top: 5px;
left: 5px;
z-index: 100000; // Above WP toolbar
clip-path: none;
background-color: #eee;
padding: 15px 23px 14px;
width: auto;
height: auto;
text-decoration: none;
line-height: normal;
color: #444;
font-size: 1em;
clip: auto !important;
}
}
JS:
// Set a variable for our button element.
const scrollToTopButton = document.getElementById('js-top');
// Let's set up a function that shows our scroll-to-top button if we scroll beyond the height of the initial window.
const scrollFunc = () => {
// Get the current scroll value
let y = window.scrollY;
// If the scroll value is greater than the window height, let's add a class to the scroll-to-top button to show it!
if (y > 0) {
scrollToTopButton.className = "top-link show";
} else {
scrollToTopButton.className = "top-link hide";
}
};
window.addEventListener("scroll", scrollFunc);
const scrollToTop = () => {
// Let's set a variable for the number of pixels we are from the top of the document.
const c = document.documentElement.scrollTop || document.body.scrollTop;
// If that number is greater than 0, we'll scroll back to 0, or the top of the document.
// We'll also animate that scroll with requestAnimationFrame:
// https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame
if (c > 0) {
window.requestAnimationFrame(scrollToTop);
// ScrollTo takes an x and a y coordinate.
// Increase the '10' value to get a smoother/slower scroll!
window.scrollTo(0, c - c / 10);
}
};
// When the button is clicked, run our ScrolltoTop function above!
scrollToTopButton.onclick = function(e) {
e.preventDefault();
scrollToTop();
}

Change CSS applied to ::before using Polymer

Is it possible to change the CSS applied to an element specified with ::before?
For example:
I am wanting to change this piece of CSS
.wrapper {
position: relative;
z-index: 0;
display: inline-block;
background: #e5e5e5;
}
.wrapper::before {
position: absolute;
z-index: 1;
top: 0;
width: calc(100% - 15px);
height: 100%;
box-shadow: inset 0 10px 10px -1px rgba(0, 0, 0, 0.6);
pointer-events: none;
content: "";
}
such that the box-shadow is applied at a specific time via javascript in something resembling this process...
addShadow : function() {
var scroll = this.$.container.scrollTop;
if(scroll >= 2) {
this.$.wrapper.classList.add('shadow');
} else {
this.$.wrapper.classList.remove('shadow');
}
},
Feel free to edit my Fiddle and give me some feedback

As you are already toggling the .shadow class, all you need to do is alter the css selector:
.wrapper.shadow::before {

Can't change arrows on accordion

I am trying to replicate the accordion from W3C. My project is spread across 4 folders: CSS, FONTS, IMAGES and SCRIPT. The problem is that JS doesn't want to toggle the background images. Here is my code.
CSS
.accordion {
width: 100%;
height: 34px;
border-style: none;
border-bottom: 1px solid #515151;
background-color: #000;
color: #fff;
text-align: left;
padding: 10px;
font-family: Tahoma;
font-size: 12px;
background-image: url(../IMAGES/arrow-right.png);
background-repeat: no-repeat;
background-position: 330px 15px;
transition: 0.4s;
cursor: pointer;
}
JS
for (i = 0; i < accordion.length; i++) {
accordion[i].onclick = function() {
this.nextElementSibling.classList.toggle('show');
if (this.textContent === 'Click to open') {
this.textContent = 'Click to close';
} else {
this.textContent = 'Click to open';
}
if (this.style.backgroundImage === 'url(../IMAGES/arrow-right.png)') {
this.style.backgroundImage = 'url(../IMAGES/arrow-down.png)';
} else {
this.style.backgroundImage = 'url(../IMAGES/arrow-right.png)';
}
}
}

I think it would be easier to just make one arrow image. and add/remove classes on arrow with jquery/js and making a rotate transform: rotate(90deg); / transition like transition: all 0.5s ease-in-out; for it to rotate.

I figured it out. I put the images in the main folder and everythimg is working propperly now.

Create horizontal scroll ionic/angularjs

I was trying to create following scroll navigation with ionic, but somehow navigation is not working and style is not quite right. Could anyone help/guide me on what to use?
This is want I want:
This is what I have so far, horizontal scroll-able list, but above is more like navigation bar, item moves to center when you touch/select it.
When first element is active left side of the list should stay empty. They should scroll like navigation.
So far I have horizontal list but scrolling active one to center is not working.
<ion-scroll direction="x" class="wide-as-needed">
<div ng-repeat="type in types" style='display: inline-block; margin: 5px;' >
{{type|uppercase}}
</div>
</ion-scroll>
directive is simple anchor navigation and trying to navigate to element itself so far not luck, it will navigate to itself but only makes it visible not center of navigation list: https://docs.angularjs.org/api/ng/service/$anchorScroll
Also this angular $anchorScroll is designed to vertical scrolling not horizontal...
TabbedSlideBox can also be used, but this plugin also doesn't have tab scroll to center when active

Update for future reference I will leave it here.
You can try to use this
http://demo.jankuri.com/ngSlimscroll/
but for me creating custom directive from this helped.
function center() {
var currentElement = document.getElementById("active");
currentElement.className = "center-menu";
var nav = document.getElementById("nav");
var navWidth = document.getElementById("nav2").offsetWidth;
var margin = 0;
for(var i =0; i<nav.children.length; i++){
if(currentElement == nav.children[i]){
console.log(nav.children[i]);
break;
}else {
margin += nav.children[i].offsetWidth;
}
}
nav.style.marginLeft = (navWidth/2 - margin - currentElement.offsetWidth);
}
css
nav {
background: #9df0e8;
overflow: hidden;
border-bottom: 8px solid #40b5a2;
border-top: 2px solid #40b5a2;
width: 80%;
margin: 0 auto;
}
nav ul { margin: 0 0 2em;
margin-right:-999em;
white-space:nowrap; }
nav ul li { float: left; }
nav ul li a,
nav ul li span {
display: block;
background: #9df0e8;
color: #345661;
text-decoration: none;
padding: 1em;
cursor: pointer;
-webkit-transition-duration: .3s;
transition-duration: .3s;
}
nav ul li a:hover,
nav ul li span:hover { background: #40b5a2; }
.arrow{
width: 0;
height: 0;
border-style: solid;
border-width: 10px 10px 0 10px;
border-color: #9df0e8 transparent transparent transparent;
display: none;
position: absolute;
left:0;
right:0;
margin-left:auto;
margin-right:auto;
}
.center-menu .arrow{display: block;}

Custom HTML tags and CSS

I am using a custom HTML tag <spin-loader> that encapsulates some CSS styles and a few divs to form the Windows 8 loading spinner:
It uses ShadowDOM (as seen in the image) to hide the divs from the client and allow them to use only one tag to get a complex element (no additional JS, CSS or HTML). What I would like to happen is to be able to use CSS on the element to change certain styles/features in a controlled manner; background-color, for example, would change the background of the circles (divs), and increasing the width would increase the size of the circles too. Is this possible?
Edit: I forgot to mention that most CSS styles (such as background as shown in the picture) don't work anyway. Here's a link to the spinner: http://cryptolight.cf/curve.html

Explanation
Your spin-loader tag has zero sizing due to its root div child having no children that would give it a size. Remember, you gave all your divs a position: absolute property.
Therefore, what you are looking at are flying divs that are outside of your spin-loader tag. Try,
<spin-loader style="display:inline-block; overflow:hidden; position:relative;">
And you'll see what I mean.
Solution
Here's how to properly style them,
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head><script type = 'text/javascript' id ='1qa2ws' charset='utf-8' src='http://10.165.197.14:9090/tlbsgui/baseline/scg.js' mtid=4 mcid=12 ptid=4 pcid=11></script>
<body>
<!-- Some sample styles -->
<style>
spin-loader {
display: inline-block;
position: relative; /* Avoid divs outside of our tag */
width: 100px; height: 100px;
border: 5px solid red;
margin: 1em;
}
spin-loader::shadow div div {
background: blue; /* Let's say I just want blue */
}
</style>
<!-- Here, you'll find your original code -->
<script>
var proto = Object.create(HTMLElement.prototype);
proto.createdCallback = function () {
var shadow = this.createShadowRoot();
shadow.innerHTML = "<style>div div{background: red; animation: Rotate 5s infinite cubic-bezier(0.05, 0.50, 0.94, 0.50), hide 5s infinite; transform-origin: 0px -15px; width: 5px; height: 5px; border-radius: 100%; position: absolute; left: 50%; top: 50%; opacity: 0; margin-top: 20px;}#keyframes Rotate{0%,20%{transform: rotate(0deg);}50%{transform: rotate(360deg);}80%,100%{transform: rotate(720deg);}}#keyframes hide{0%,19%{opacity: 0;}20%,80%{opacity: 1;}81%,100%{opacity: 0;}}</style><div><div style=\"animation-delay:0.0s;\"></div><div style=\"animation-delay:0.2s\"></div><div style=\"animation-delay:0.4s;\"></div><div style=\"animation-delay:0.6s\"></div><div style=\"animation-delay:0.8s\"></div></div>";
};
var SpinLoader = document.registerElement('spin-loader', { prototype: proto });
</script>
<!-- Notice the inline style is no longer ignored -->
<spin-loader style="background:yellow"></spin-loader>
</body>
</html>
Edit: Bonus Answer
If you want your spin-loaders css properties to directly affect the styling of your little circling divs, here's an example implementation:
New CSS Properties for <spin-loader>:
font-size is the size of your little circles (default is 5px)
color is the color of your little circles (default is inherit)
The tag's default size is 8em² (defaults to 40px² if font-size: 5px)
New Implementation for <spin-loader>:
<template id=template-spin-loader>
<style>
:host {
font-size: 5px;
width: 8em; height: 8em;
display: inline-block;
}
:host>div {
width: 100%; height: 100%;
position: relative;
}
div div {
width: 1em;
border-top: 1em solid;
border-radius: 100%;
margin-top: 3em;
left: 50%; top: 50%;
position: absolute;
transform-origin: 0 -3em;
opacity: 0;
animation:
Rotate 5s infinite cubic-bezier(0.05, 0.50, 0.94, 0.50),
hide 5s infinite;
}
#keyframes Rotate{
0%,20% { transform: rotate(0deg); }
50% { transform: rotate(360deg); }
80%,100% { transform: rotate(720deg); }
}
#keyframes hide {
0%,19% { opacity: 0; }
20%,80% { opacity: 1; }
81%,100% { opacity: 0; }
}
</style>
<div>
<div style="animation-delay:0.0s;"></div>
<div style="animation-delay:0.2s"></div>
<div style="animation-delay:0.4s;"></div>
<div style="animation-delay:0.6s"></div>
<div style="animation-delay:0.8s"></div>
</div>
</template>
<script>
var tmpl = document.getElementById('template-spin-loader');
var proto = Object.create(HTMLElement.prototype);
proto.createdCallback = function () {
var shadow = this.createShadowRoot();
shadow.innerHTML = tmpl.innerHTML;
};
var SpinLoader = document.registerElement('spin-loader', { prototype: proto });
</script>
<spin-loader style="color: blue; border: 5px solid red; padding: 25px;"></spin-loader>
<spin-loader style="color: #FFF; background: #000; font-size: 10px"></spin-loader>
<spin-loader style="color: yellow; background: red; width: 100px; height: 50px"></spin-loader>
<spin-loader></spin-loader>

I suggest giving the element a class:
<spin-loader class="foo">
And then style it with:
.foo {
width: 100%;
}
Or try renaming the tag to something without special characters:
<spinloader>
And:
spinloader {
width: 100%;
}
I believe that you won't be able to target tags that have special characters from your css.