1

I have created a fade-in effect of single elements (.boxes > div) when an user scrolls down the website. I check with Javascript if the element just scrolled into the view and then add the class .fadeInUp to add the animation effect.

This is how I accomplish to fade in another element after another element with animation-delay:

.fadeInUp {
    & + .fadeInUp {
        animation-delay: 300ms;
        & + .fadeInUp {
            animation-delay: 600ms;
            & + .fadeInUp {
                animation-delay: 900ms;
                & + .fadeInUp {
                    animation-delay: 1200ms;
                    & + .fadeInUp {
                        animation-delay: 1500ms;
                    }
                }
            }
        }
    }

    opacity: 0;
    animation: fadeInUp 1000ms forwards;
}

However, I want to shorten my SCSS code to select the next sibling class with the same class name, because if I add boxes to the HTML part, I also need to add the animation-delay to the SCSS part.

Question:

Is there an option to shorten this behaviour with native CSS (or SCSS alternatively) without knowing how many boxes will be there? Something like 

& + * { ... }

but specific to the class .fadeInUp and also increasing the animation-delay value by 300ms with each next sibling class?

I have created this pen to demonstrate my question and make it more clear:

CodePen: Delayed Boxes FadeIn-Animation

enter image description here

AlexioVay
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  • I think in the future this could be the solution you are looking for: https://stackoverflow.com/questions/43539203/use-css-counter-in-calc. For now, I'd add a simple `e.style.animationDelay=i*300+"ms";` in your loop and let javascript do the dirty work ;-) – ReSedano Jan 06 '20 at 09:41
  • Thanks for this useful link and your js suggestion! @ReSedano I also thought of that but wanted to know first if there is an CSS possibility. Would accept your comment as answer if you'd post it. :) – AlexioVay Jan 06 '20 at 10:18
  • ok. Thank you very much! I added another point of view to solve your problem :-) – ReSedano Jan 06 '20 at 11:04

1 Answers1

1

As far as I know, I think it is not possible to do this with a pure CSS solution.

In the future this could be the solution you are looking for: stackoverflow.com/questions/43539203/use-css-counter-in-calc. For now, I'd add a simple e.style.animationDelay=i*300+"ms"; in your loop and let javascript do... the "dirty work".

function inView(el) {
    let box = el.getBoundingClientRect();
    return box.top < window.innerHeight && box.bottom >= 0;
}

const boxes = document.querySelectorAll('.boxes >  div');


window.onscroll = (w) => {
  boxes.forEach((e, i) => {
    e.style.animationDelay=i*300+"ms";
    if (inView(e)) {
        e.classList.add('fadeInUp');
    }

  });
}
body {
  height: 2000px;
  display: grid;
  justify-items: center;
}

.boxes {
  margin-top: 1000px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: 300px;
  grid-gap: 30px;
  justify-items: center;
  width: 80%;
}
  
.boxes div {
  height: 300px;
  width: 300px;
  box-shadow: 0 0 15px #ccc;
  background-image: url(https://images.unsplash.com/photo-1542141372-98a047557466?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
  background-size: cover;
}

.boxes div:nth-child(2) {
  background-image: url(https://images.unsplash.com/photo-1522057306606-8d84daa75e87?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(3) {
  background-image: url(https://images.unsplash.com/photo-1505870136463-c17bc84b30a2?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(4) {
  background-image: url(https://images.unsplash.com/photo-1524419986249-348e8fa6ad4a?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(5) {
  background-image: url(https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(6) {
  background-image: url(https://images.unsplash.com/photo-1514828980084-9462f7d03afc?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}    

.fadeInUp {
  opacity: 0;
  animation: fadeInUp 1000ms forwards;
}

@keyframes fadeInUp {
    0% {
        opacity: 0;
        transform: translateY(20px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}
<html>
  <body>
    <div class="boxes">
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
    </div>
  </body>
</html>

P.S. what about to use: nth-child(n+...) to create a similar result? Something like:

.boxes div:nth-child(3n+1){
  animation-delay:300ms;
}

.boxes div:nth-child(3n+2){
  animation-delay:600ms;
}

.boxes div:nth-child(3n+3){
  animation-delay:900ms;
}


function inView(el) {
    let box = el.getBoundingClientRect();
    return box.top < window.innerHeight && box.bottom >= 0;
}

const boxes = document.querySelectorAll('.boxes >  div');


window.onscroll = (w) => {
  boxes.forEach((e, i) => {
    if (inView(e)) {
        e.classList.add('fadeInUp');
    }
  });
}
body {
  height: 2000px;
  display: grid;
  justify-items: center;
}

.boxes {
  margin-top: 1000px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: 300px;
  grid-gap: 30px;
  justify-items: center;
  width: 80%;
}
  
.boxes div {
  height: 300px;
  width: 300px;
  box-shadow: 0 0 15px #ccc;
  background-image: url(https://images.unsplash.com/photo-1542141372-98a047557466?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
  background-size: cover;
}

.boxes div:nth-child(2) {
  background-image: url(https://images.unsplash.com/photo-1522057306606-8d84daa75e87?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(3) {
  background-image: url(https://images.unsplash.com/photo-1505870136463-c17bc84b30a2?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(4) {
  background-image: url(https://images.unsplash.com/photo-1524419986249-348e8fa6ad4a?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(5) {
  background-image: url(https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}

.boxes div:nth-child(6) {
  background-image: url(https://images.unsplash.com/photo-1514828980084-9462f7d03afc?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
}    

.fadeInUp {
  opacity: 0;
  animation: fadeInUp 1000ms forwards;
}

.boxes div:nth-child(3n+1){
  animation-delay:300ms;
}

.boxes div:nth-child(3n+2){
  animation-delay:600ms;
}

.boxes div:nth-child(3n+3){
  animation-delay:900ms;
}

@keyframes fadeInUp {
    0% {
        opacity: 0;
        transform: translateY(20px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}
<html>
  <body>
    <div class="boxes">
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
    </div>
  </body>
</html>
ReSedano
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