Activate CSS3 animation when the content scrolls into view
JqueryHtmlCssScrollCss AnimationsJquery Problem Overview
I have a bar chart that animates with CSS3 and the animation currently activates as the page loads.
The problem I have is that the given bar chart is placed off screen due to lots of content before it so by the time a user scrolls down to it, the animation has already finished.
I was looking for ways either through CSS3 or jQuery to only activate the CSS3 animation on the bar chart when the viewer sees the chart.
<div>lots of content here, it fills the height of the screen and then some</div>
<div>animating bar chat here</div>
If you scroll down really fast right after page load, you can see it animating.
Here is a jsfiddle of my code. Also, I dont know if this matters, but I have several instances of this bar chart on the page.
I have come across a jQuery plug-in called waypoint but I had absolutely no luck getting it to work.
If someone could point me in the right direction, it would be really helpful.
Thanks!
Jquery Solutions
Solution 1 - Jquery
Capture scroll events
This requires using JavaScript or jQuery to capture scroll events, checking each time a scroll event fires to see if the element is in view.
Once the element is in view, start the animation. In the code below, this is done by adding a "start" class to the element, that triggers the animation.
HTML
<div class="bar">
<div class="level eighty">80%</div>
</div>
CSS
.eighty.start {
width: 0px;
background: #aae0aa;
-webkit-animation: eighty 2s ease-out forwards;
-moz-animation: eighty 2s ease-out forwards;
-ms-animation: eighty 2s ease-out forwards;
-o-animation: eighty 2s ease-out forwards;
animation: eighty 2s ease-out forwards;
}
jQuery
function isElementInViewport(elem) {
var $elem = $(elem);
// Get the scroll position of the page.
var scrollElem = ((navigator.userAgent.toLowerCase().indexOf('webkit') != -1) ? 'body' : 'html');
var viewportTop = $(scrollElem).scrollTop();
var viewportBottom = viewportTop + $(window).height();
// Get the position of the element on the page.
var elemTop = Math.round( $elem.offset().top );
var elemBottom = elemTop + $elem.height();
return ((elemTop < viewportBottom) && (elemBottom > viewportTop));
}
// Check if it's time to start the animation.
function checkAnimation() {
var $elem = $('.bar .level');
// If the animation has already been started
if ($elem.hasClass('start')) return;
if (isElementInViewport($elem)) {
// Start the animation
$elem.addClass('start');
}
}
// Capture scroll events
$(window).scroll(function(){
checkAnimation();
});
Solution 2 - Jquery
Sometimes you need the animation to always occur when the element is in the viewport. If this is your case, I slightly modified Matt jsfiddle code to reflect this.
jQuery
// Check if it's time to start the animation.
function checkAnimation() {
var $elem = $('.bar .level');
if (isElementInViewport($elem)) {
// Start the animation
$elem.addClass('start');
} else {
$elem.removeClass('start');
}
}
Solution 3 - Jquery
In order to activate a CSS animation, a class needs to be added to the element when this becomes visible. As other answers have indicated, JS is required for this and Waypoints is a JS script that can be used.
> Waypoints is the easiest way to trigger a function when you scroll to > an element.
Up to Waypoints version 2, this used to be a relatively simple jquery plugin. In version 3 and above (this guide version 3.1.1) several features have been introduced. In order to accomplish the above with this, the 'inview shortcut' of the script can be used:
-
Download and add the script files from this link or from Github (version 3 is not yet available through CDNJS, although RawGit is always an option too).
-
Add the script to your HTML as usual.
<script src="/path/to/lib/jquery.waypoints.min.js"></script> <script src="/path/to/shortcuts/inview.min.js"></script>
-
Add the following JS code, replacing
#myelement
with the appropriate HTML element jQuery selector:$(window).load(function () { var in_view = new Waypoint.Inview({ element: $('#myelement')[0], enter: function() { $('#myelement').addClass('start'); }, exit: function() { // optionally $('#myelement').removeClass('start'); } }); });
We use $(window).load()
for reasons explained here.
Updated Matt's fiddle here.
Solution 4 - Jquery
You do not need to capture scroll events anymore
Since 2020, every browser is able to notify if an element is visible in your viewport.
With intersection observer.
I posted the code here: https://stackoverflow.com/a/62536793/5390321
Solution 5 - Jquery
In addition to these answers please consider these points :
1- Checking the element in view has many considerations :
https://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
2- If someone wanted to have more control over the animation (e.g. set "the animation type" and "start delay") here is a good article about it :
http://blog.webbb.be/trigger-css-animation-scroll/
3- And also it seems that calling addClass without a delay (using setTimeout) is not effective.
Solution 6 - Jquery
CSS FOR TRIGGER :
<style>
.trigger{
width: 100px;
height: 2px;
position: fixed;
top: 20%;
left: 0;
background: red;
opacity: 0;
z-index: -1;
}
</style>
<script>
$('body').append('<div class="trigger js-trigger"></div>');
$(document).scroll(function () {
$('YOUR SECTIONS NAME').each(function () {
let $this = $(this);
if($this.offset().top <= $('.js-trigger').offset().top) {
if (!$this.hasClass('CLASS NAME FOR CHECK ACTIVE SECTION')) {
$this
.addClass('currSec')
.siblings()
.removeClass('currSec');
}
}
});
});
</script>