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HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

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();
}
              
            
!
999px

Console