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The onanimationiteration
property of the GlobalEventHandlers
mixin is the EventHandler
for processing animationiteration
events.
The animationiteration
event is sent when a CSS animation reaches the end of an iteration. An iteration ends when a single pass through the sequence of animation instructions is completed by executing the last animation step.
Syntax
var animIterationHandler = target.onanimationiteration; target.onanimationiteration = Function
Value
A Function
to be called when an animationiteration
event occurs indicating that a CSS animation has reached the end of an iteration while running on the target
, where the target object is an HTML element (HTMLElement
), document (Document
), or window (Window
). The function receives as input a single parameter: an AnimationEvent
object describing the event which occurred.
Example
Let's create an animation which automatically pauses at the end of each iteration, allowing the user to choose whether or not to start the next iteration. Much of this code is the same as in other examples of animation events, so it may look familiar.
HTML
<div class="main">
<div id="box">
<div id="text">Box</div>
</div>
</div>
<div class="button" id="play">
Begin Demonstration
</div>
CSS
:root {
--boxwidth:50px;
}
.main {
width: 300px;
height:300px;
border: 1px solid black;
}
.button {
cursor: pointer;
width: 300px;
border: 1px solid black;
font-size: 16px;
text-align: center;
margin-top: 0;
padding-top: 2px;
padding-bottom: 4px;
color: white;
background-color: darkgreen;
font: 14px "Open Sans", "Arial", sans-serif;
}
#text {
width: 46px;
padding: 10px;
position: relative;
text-align: center;
align-self: center;
color: white;
font: bold 1.4em "Lucida Grande", "Open Sans", sans-serif;
}
Leaving out some bits of the CSS that don't matter for the discussion here, let's take a look at the styles for the box that we're animating. First is the box itself. We set its size, position, color, and layout. Note that there's nothing there about animation. That's because we don't want the box to start animating right away. We'll add the animation
style later to start animating the box.
#box {
width: var(--boxwidth);
height: var(--boxwidth);
left: 0;
top: 0;
border: 1px solid #7788FF;
margin: 0;
position: relative;
background-color: #2233FF;
display: flex;
justify-content: center;
animation: 2s ease-in-out 0s infinite alternate both paused slideBox;
}
The animation's keyframes are defined next; they describe an animation which causes the box to migrate from the top-left corner of the container to the bottom-right corner.
@keyframes slideBox {
from {
left:0;
top:0;
}
to {
left:calc(100% - var(--boxwidth));
top:calc(100% - var(--boxwidth))
}
}
JavaScript
Some JavaScript code will need to be written to handle the click on the button to start the next iteration. Let's have a look.
var box = document.getElementById("box");
var iterationCounter = 0;
box.onanimationiteration = function(event) {
box.style.animationPlayState = "paused";
document.getElementById("play").innerHTML = "Start Iteration #" + (iterationCounter+1);
};
This sets up two global variables: box
, which references the "box"
element that we're animating, and iterationCounter
, which is initially zero, which indicates how many iterations of the animation have occurred.
The onanimationiteration event handler is then set up. It simply sets the box's animation-play-state
to "paused", then updates the text displayed in the button to indicate that clicking the button will start playing the next iteration of theanimation.
Finally, we set up a handler for a click on the button that runs the animation:
document.getElementById("play").addEventListener("click", function(event) {
box.style.animationPlayState = "running";
iterationCounter++;
}, false);
This sets the box element's animation-play-state
to "running" and increments the iteration counter. That's all there is to it!
Result
Assembled together, you get this:
Each time the box reaches the opposing corner, it stops, with the button reflecting which iteration number is up next, until you click the button to run the next iteration.
Specification
Specification | Status | Comment |
CSS AnimationsThe definition of 'onanimationiteration' in that specification. | Working Draft |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
onanimationiteration
|
Chrome Full support Yes Full support Yes Full support Yes Alternate Name' Uses the non-standard name: |
Edge Full support ≤79 Full support ≤79 Full support ≤79 Alternate Name' Uses the non-standard name: |
Firefox
Full support 51 |
IE
? |
Opera
? |
Safari
Full support 9 |
WebView Android Full support Yes Full support Yes Full support Yes Alternate Name' Uses the non-standard name: |
Chrome Android Full support Yes Full support Yes Full support Yes Alternate Name' Uses the non-standard name: |
Firefox Android
Full support 51 |
Opera Android
? |
Safari iOS
Full support 9 |
Samsung Internet Android Full support Yes Full support Yes Full support Yes Alternate Name' Uses the non-standard name: |
Legend
- Full support
- Full support
- Compatibility unknown
- Compatibility unknown
- Uses a non-standard name.'
- Uses a non-standard name.
See also
- The
animationiteration
event, which triggers this event handler AnimationEvent
GlobalEventHandlers.onanimationiteration by Mozilla Contributors is licensed under CC-BY-SA 2.5.