I have a short javascript function which applies an animation class to a div when it is "scrolled" into view. This works great for one div with these classes. But how do I apply this to multiple elements with these classes? I have multiple elements of .square and .square-wrapper down the page, and I want each one to animate in when the user scrolls near it. Here is the function which only applies .square-animate to the first element :
<script>
const observer = new IntersectionObserver(entries => {
entries.forEach(entry => {
const square = entry.target.querySelector('.square');
if (entry.isIntersecting) {
square.classList.add('square-animation');
return; // if we added the class, exit the function
}
// We're not intersecting, so remove the class!
square.classList.remove('square-animation');
});
});
observer.observe(document.querySelector('.square-wrapper'));
</script>
The HTML part looks something like this:
<div class="container row square-wrapper">
<div class="col s12 m4 square">
// some content here
</div>
</div>
<div class="container row square-wrapper">
<div class="col s12 m4 square">
// some content here
</div>
</div>
<div class="container row square-wrapper">
<div class="col s12 m4 square">
// some content here
</div>
</div>
I don't know if there is a smartest solution. In this mine, I call observe on each target element that you want observe. The various calls don't override the previous one, but listen to all.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
.square-animation {
animation: coloraGraduale 2s forwards;
}
@keyframes coloraGraduale {
from {
background-color: white;
}
to {
background-color: red;
}
}
</style>
</head>
<body>
<div style="height: 1000px"></div>
<div class="container row square-wrapper">
<div class="col s12 m4 square">
<p>
Lorem ipsum dolor sit amet consectetur adipisicing elit. Perspiciatis
fuga dolore impedit architecto cupiditate dignissimos rerum ut
deleniti. Laudantium harum expedita a. Eius velit dolorum laborum modi
quidem voluptate ullam!
</p>
</div>
</div>
<div class="container row square-wrapper">
<div class="col s12 m4 square">
<p>
Lorem ipsum dolor sit amet consectetur adipisicing elit. Perspiciatis
fuga dolore impedit architecto cupiditate dignissimos rerum ut
deleniti. Laudantium harum expedita a. Eius velit dolorum laborum modi
quidem voluptate ullam!
</p>
</div>
</div>
<div class="container row square-wrapper">
<div class="col s12 m4 square">
<p>
Lorem ipsum dolor sit amet consectetur adipisicing elit. Perspiciatis
fuga dolore impedit architecto cupiditate dignissimos rerum ut
deleniti. Laudantium harum expedita a. Eius velit dolorum laborum modi
quidem voluptate ullam!
</p>
</div>
</div>
<script>
const observer = new IntersectionObserver((entries) => {
entries.forEach((entry) => {
const square = entry.target.querySelector(".square");
if (entry.isIntersecting) {
square.classList.add("square-animation");
return; // if we added the class, exit the function
}
// We're not intersecting, so remove the class!
square.classList.remove("square-animation");
});
});
let elements = document.querySelectorAll(".square-wrapper");
for (let element of elements) {
observer.observe(element);
}
</script>
</body>
</html>