How to prevent a CSS keyframe animation from running on page load?

Css Problem Overview

I have a div in which I animate the content:

#container {
  position: relative;
  width: 100px;
  height: 100px;
  border-style: inset;
}
#content {
  visibility: hidden;
  -webkit-animation: animDown 1s ease;
  position: absolute;
  top: 100px;
  width: 100%;
  height: 100%;
  background-color: lightgreen;
}
#container:hover #content {
  -webkit-animation: animUp 1s ease;
  animation-fill-mode: forwards;
  -webkit-animation-fill-mode: forwards;
}
@-webkit-keyframes animUp {
  0% {
    -webkit-transform: translateY(0);
    visibility: hidden;
    opacity: 0;
  }
  100% {
    -webkit-transform: translateY(-100%);
    visibility: visible;
    opacity: 1;
  }
}
@-webkit-keyframes animDown {
  0% {
    -webkit-transform: translateY(-100%);
    visibility: visible;
    opacity: 1;
  }
  100% {
    -webkit-transform: translateY(0);
    visibility: hidden;
    opacity: 0;
  }
}

<div id="container">
  <div id="content"></div>
</div>

On hover, the content slides into the container div. When I refresh the page and the page loads, the #content's animDown animation will run, and I'd prefer it to run only after a hover event.

Is there a way to do this pure CSS, or I have to figure something out in JS?

http://jsfiddle.net/d0yhve8y/

Css Solutions

Solution 1 - Css

I always set preload class to body with animation time value 0 and its working pretty well. I have some back going transitions so I have to remove load animation to them too. I solved this by temporary setting animation time to 0. You can change transitions to match yours.

HTML

... <body class="preload">...

CSS is setting animation to 0s

body.preload *{
animation-duration: 0s !important;
-webkit-animation-duration: 0s !important;
transition:background-color 0s, opacity 0s, color 0s, width 0s, height 0s, padding 0s, margin 0s !important;}

JS will remove class after some delay so animations can happen in normal time :)

setTimeout(function(){
	document.body.className="";
},500);

Solution 2 - Css

Solution 1 - Add down animation on first hover

Probably the best option is to not put the down animation on until the user has hovered over the container for the first time.

This involves listening to the mouseover event then adding a class with the animation at that point, and removing the event listener. The main (potential) downside of this is it relies on Javascript.

;(function(){
    var c = document.getElementById('container');
    function addAnim() {
        c.classList.add('animated')
        // remove the listener, no longer needed
        c.removeEventListener('mouseover', addAnim);
    };

    // listen to mouseover for the container
    c.addEventListener('mouseover', addAnim);
})();

#container {
    position:relative;
    width:100px;
    height:100px;
    border-style:inset;
}
#content {
    position:absolute;
    top:100px;
    width:100%;
    height:100%;
    background-color:lightgreen;
    opacity:0;
}

/* This gets added on first mouseover */
#container.animated #content {
    -webkit-animation:animDown 1s ease;
}

#container:hover #content {
    -webkit-animation:animUp 1s ease;
    animation-fill-mode:forwards;
    -webkit-animation-fill-mode:forwards;
}

@-webkit-keyframes animUp {
    0% {
        -webkit-transform:translateY(0);
        opacity:0;
    }
    100% {
        -webkit-transform:translateY(-100%);
        opacity:1;
    }
}
@-webkit-keyframes animDown {
    0% {
        -webkit-transform:translateY(-100%);
        opacity:1;
    }
    100% {
        -webkit-transform:translateY(0);
        opacity:0;
    }
}

<div id="container">
    <div id="content"></div>
</div>

Solution 2 - play animation hidden

Another way around this is to initially hide the element, make sure the animation plays while it is hidden, then make it visible. The downside of this is that the timing could be slightly off and it is made visible too early, and also the hover isn't available straight away.

This requires some Javascript which waits for the length of the animation and only then makes #content visible. This means you also need to set the initial opacity to 0 so it doesn't appear on load and also remove the visibility from the keyframes - these aren't doing anything anyway:

// wait for the animation length, plus a bit, then make the element visible
window.setTimeout(function() {
    document.getElementById('content').style.visibility = 'visible';
}, 1100);

#container {
    position:relative;
    width:100px;
    height:100px;
    border-style:inset;
}

#content {
    visibility:hidden;
    -webkit-animation:animDown 1s ease;
    position:absolute;
    top:100px;
    width:100%;
    height:100%;
    background-color:lightgreen;
    opacity:0;
}

#container:hover #content {
    -webkit-animation:animUp 1s ease;
    animation-fill-mode:forwards;
    -webkit-animation-fill-mode:forwards;
}

@-webkit-keyframes animUp {
    0% {
        -webkit-transform:translateY(0);
        opacity:0;
    }
    100% {
        -webkit-transform:translateY(-100%);
        opacity:1;
    }
}

@-webkit-keyframes animDown {
    0% {
        -webkit-transform:translateY(-100%);
        opacity:1;
    }
    100% {
        -webkit-transform:translateY(0);
        opacity:0;
    }
}

<div id="container">
    <div id="content"></div>
</div>

Solution 3 - Use transitions

In your scenario, you can make this CSS only by replacing the keyframes with a transition instead, so it starts with opacity:0 and just the hover has a change in opacity and the transform:

#container {
    position:relative;
    width:100px;
    height:100px;
    border-style:inset;
}

#content {
    position:absolute;
    top:100px;
    width:100%;
    height:100%;
    background-color:lightgreen;

    /* initial state - hidden */
    opacity:0;
    /* set properties to animate - applies to hover and revert */
    transition:opacity 1s, transform 1s;
}

#container:hover #content {
    /* Just set properties to change - no need to change visibility */
    opacity:1;
    -webkit-transform:translateY(-100%);
    transform:translateY(-100%);
}

<div id="container">
    <div id="content"></div>
</div>

Solution 3 - Css

> Is there a way to do this pure CSS ?

Yes, absolutely : See the fork http://jsfiddle.net/5r32Lsme/2/ There is really no need for JS.

> and I'd prefer it to run only after a hover event.

So you need to tell CSS what happens when it is NOT a hover event as well - in your example :

#container:not(:hover) #content {
  visibility: hidden;
  transition: visibility 0.01s 1s;
}

But there are two things to note:

The transition delay above should match your animation duration
You can't use the property which you use to hide the animation onLoad in the animation. If you do need visibility in the animation, hide the animation initially like e.g.

#container:not(:hover) #content {
  top: -8000px;
  transition: top 0.01s 1s;
}

A sidenote:

It is recommended to put native CSS properties after prefixed ones, so it should be

-webkit-animation-fill-mode: forwards;
animation-fill-mode: forwards;

and now there is a native transform

-webkit-transform: translateY(0);
transform: translateY(0);

Solution 4 - Css

This is not pure CSS but maybe someone will stumble across this thread as I did:

In React I solved this by setting a temporary class in ComponentDidMount() like so:

componentDidMount = () => {
    document.getElementById("myContainer").className =
        "myContainer pageload";
};

and then in css:

.myContainer.pageload {
    animation: none;
}

.myContainer.pageload * {
    animation: none;
}

If you are not familiar the " *" (n.b. the space) above means that it applies to all descendents of the element as well. The space means all descendents and the asterisk is a wildcard operator that refers to all types of elements.

Solution 5 - Css

If you're looking at this after 2019, a better solution is this:

let div = document.querySelector('div')
document.addEventListener('DOMContentLoaded', () => {
    // Adding timeout to simulate the loading of the page
    setTimeout(() => {
        div.classList.remove('prevent-animation')
    }, 2000)
    
    document.querySelector('button').addEventListener('click', () => {
        if(div.classList.contains('after')) {
            div.classList.remove('after')
        } else {
            div.classList.add('after')
        }
    })
})

div {
    background-color: purple;
    height: 150px;
    width: 150px;
}

.animated-class {
    animation: animationName 2000ms;
}

.animated-class.prevent-animation {
    animation-duration: 0ms;
}

.animated-class.after {
    animation: animation2 2000ms;
    background-color: orange;
}

@keyframes animationName {
    0% {
        background-color: red;
    }
    50% {
        background-color: blue;
    }
    100% {
        background-color: purple;
    }
}

@keyframes animation2 {
    0% {
        background-color: salmon;
    }
    50% {
        background-color: green;
    }
    100% {
      background-color: orange;
    }
}

<div class="animated-class prevent-animation"></div>
<button id="btn">Toggle between animations</button>

Solution 6 - Css

It's always better a solution without relying on javascript.

The ones with CSS mentioned here are ok. The idea of hiding when not on mouse hover is fine for some situations, but I noticed that if I wanted the animation to happen when the mouse moves out of the element, it wouldn't happen because of the :not(:hover) rule.

The solution I came up worked best for me, by adding a animation to the parent element, that only adds opacity at the end with the same duration. Easier shown than explain:

I grabbed the fiddle made by @sebilasse and @9000 and I added the below code there:

https://jsfiddle.net/marcosrego/vqo3sr8z/2/

#container{
	animation: animShow 1s forwards;    
}

@keyframes animShow {
    0% {
      opacity: 0;
    }
    99% {
      opacity: 0;
    }
    100% {
      opacity: 1;
    }
}

Solution 7 - Css

Rotation animation that (appears) not to run until needed.
The CSS below allows for up and down arrows for showing menu items. The animation does not appear to run on page load, but it really does.

@keyframes rotateDown {
   from { transform: rotate(180deg); }
   to   { transform: rotate(0deg); }
}

@keyframes rotateUp {
   from { transform: rotate(180deg); }
   to   { transform: rotate(0deg); }
}

div.menu input[type='checkbox'] + label.menu::before {
   display            :inline-block;
   content            : "▼";
   color              : #b78369;
   opacity            : 0.5;
   font-size          : 1.2em;
}

div.menu input[type='checkbox']:checked + label.menu::before {
   display            : inline-block;
   content            : "▲";
   color              : #b78369;
   opacity            : 0.5;
   font-size          : 1.2em;
}

div.menu input[type='checkbox'] + label.menu {
   display            : inline-block;
   animation-name     : rotateDown;
   animation-duration : 1ms;
}

div.menu input[type='checkbox']:checked + label.menu {
   display            : inline-block;
   animation-name     : rotateUp;
   animation-duration : 1ms;
}

div.menu input[type='checkbox'] + label.menu:hover {
   animation-duration : 500ms;
}

div.menu input[type='checkbox']:checked + label.menu:hover {
   animation-duration : 500ms;
}

From top to bottom:

Create the rotations. For this there are two... one for the down arrow and one for the up arrow. Two arrows are needed, because, after the rotation, they return to their natural state. So, the down arrow starts up and rotates down, while the up arrow starts down and rotates up.
Create the little arrows. This is a straight forward implementation of ::before
We put the animation on the label. There is nothing special, there, except that the animation duration is 1ms.
The mouse drives the animation speed. When the mouse hovers over the element, the animation-duration is set to enough time to seem smooth.

Working on my site

Solution 8 - Css

Having had to solve a similar challenge, a neat CSS-only trick morewry posted already back in 2013 is to create an animation that initially is in a paused play-state on a keyframe hiding the element:

#content {
  animation:animDown 1s ease, hasHovered 1ms paused;
  animation-fill-mode: forwards; /* for both animations! */
}
#container:hover #content {
  animation:animUp 1s ease, hasHovered 1ms;
}

/* hide #content element until #container has been hovered over */
@keyframes hasHovered {
  0% { visibility: hidden; }     /* property has to be removed */
  100% { visibility: visible; }  /* from the other animations! */
}

When hovering, the very brief animated transformation is applied and stays in the 100%-keyframe-state even after mouse-leave thanks to the animation-fill-mode.

For how to set animation sub-properties with multiple animations, see https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Animations/Using_CSS_animations#setting_multiple_animation_property_values

Solution 9 - Css

Building off of Tominator's answer, in React, you can apply it per component like so:

import React, { Component } from 'react'

export default class MyThing extends Component {
  constructor(props) {
    super(props);

    this.state = {
      preloadClassName: 'preload'
    }
  }

  shouldComponentUpdate(nextProps, nextState) {
    return nextState.preloadClassName !== this.state.preloadClassName;
  }

  componentDidUpdate() {
    this.setState({ preloadClassName: null });
  }

  render() {
    const { preloadClassName } = this.state;

    return (
      <div className={`animation-class ${preloadClassName}`}>
        <p>Hello World!</p>
      </div>
    )
  }
}

and the css class:

.preload * {
  -webkit-animation-duration: 0s !important;
  animation-duration: 0s !important;
  transition: background-color 0s, opacity 0s, color 0s, width 0s, height 0s, padding 0s, margin 0s !important;
}

Content Type	Original Author	Original Content on Stackoverflow
Question	Szabolcs	View Question on Stackoverflow
Solution 1 - Css	Tominator	View Answer on Stackoverflow
Solution 2 - Css	Rhumborl	View Answer on Stackoverflow
Solution 3 - Css	sebilasse	View Answer on Stackoverflow
Solution 4 - Css	ClownBaby	View Answer on Stackoverflow
Solution 5 - Css	Guilherme P.	View Answer on Stackoverflow
Solution 6 - Css	Marcos Rego	View Answer on Stackoverflow
Solution 7 - Css	user1126454	View Answer on Stackoverflow
Solution 8 - Css	eMPee584	View Answer on Stackoverflow
Solution 9 - Css	VocoJax	View Answer on Stackoverflow