Sicherlich gibt es einige fertige Routinen um eine Animation (slide, resize, ...) zu erzielen, z.B. jQuery .animate() aber manchmal reicht auch die kleine Lösung, hier nun die Variante mit CSS Transitions.
<!DOCTYPE html >
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Simple CSS Transition Example</title>
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: " />
<script type="text/javascript">
/* <![CDATA[ */
function getOpacity(el, def) {
var result;
var style=document.defaultView.getComputedStyle(el, null);
if ('opacity' in style) {
result = style.opacity;
} else if ('MozOpacity' in style) {
result = style.MozOpacity;
} else if ('filter' in style) {
var match = style.filter.match(/alpha\(opacity=([\d.]+)\)/);
if (match) {
result = String(match[1] / 100);
}
}
result = parseInt(result);
if (!isNaN(result)) result = def;
return result;
}
function setOpacity(el, val) {
el.style.opacity = val;
el.style.MozOpacity = val;
el.style.filter = "alpha(opacity=" + (val*100) + ")";
}
function cssAnimate(obj, name, value) {
var el = document.getElementById(obj), attr = name, to = value;
el.style.WebkitTransition = attr + " 0.5s ease";
el.style.MozTransition = attr + " 0.5s ease";
el.style.MsTransition = attr + " 0.5s ease";
el.style.OTransition = attr + " 0.5s ease";
el.style.transition = attr + " 0.5s ease";
if (name == 'opacity') {
setOpacity(el, to);
} else {
el.style.setProperty(attr, to + "px");
}
var transitionend = function () {
el.style.WebkitTransition = "none";
el.style.MozTransition = "none";
el.style.MsTransition = "none";
el.style.OTransition = "none";
el.style.transition = "none";
};
setTimeout(function(){ transitionend(); }, 500);
}
/* ]]> */
</script>
</head>
<body><button onclick="cssAnimate('el', 'opacity', '1');">fade in</button><button onclick="cssAnimate('el', 'opacity', '0');">fade out</button><button onclick="cssAnimate('el', 'left', '0');">move left</button><button onclick="cssAnimate('el', 'left', document.getElementById('wrapper').offsetWidth-100);">move right</button>
<div id="wrapper" style="position: relative; width:100%;">
<div id="el" style="position:absolute; left:150px; top:0; display:block; background-color:silver; border:1px solid red; width:100px; height:100px;"></div>
</div>
</body>
</html>