.fadeTo()
.fadeTo( duration, opacity [, callback] ) Returns: jQuery
Description: Adjust the opacity of the matched elements.
-
version added: 1.0.fadeTo( duration, opacity [, callback] )
durationA string or number determining how long the animation will run.
opacityA number between 0 and 1 denoting the target opacity.
callbackA function to call once the animation is complete.
-
version added: 1.4.3.fadeTo( duration, opacity [, easing] [, callback] )
durationA string or number determining how long the animation will run.
opacityA number between 0 and 1 denoting the target opacity.
easingA string indicating which easing function to use for the transition.
callbackA function to call once the animation is complete.
The .fadeTo() method animates the opacity of the matched elements.
Durations are given in milliseconds; higher values indicate slower animations, not faster ones. The strings 'fast' and 'slow' can be supplied to indicate durations of 200 and 600 milliseconds, respectively. If any other string is supplied, the default duration of 400 milliseconds is used. Unlike the other effect methods, .fadeTo() requires that duration be explicitly specified.
If supplied, the callback is fired once the animation is complete. This can be useful for stringing different animations together in sequence. The callback is not sent any arguments, but this is set to the DOM element being animated. If multiple elements are animated, it is important to note that the callback is executed once per matched element, not once for the animation as a whole.
We can animate any element, such as a simple image:
<div id="clickme">
Click here
</div>
<img id="book" src="book.png" alt="" width="100" height="123" />
With the element initially shown, we can dim it slowly:
$('#clickme').click(function() {
$('#book').fadeTo('slow', 0.5, function() {
// Animation complete.
});
});
With duration set to 0, this method just changes the opacity CSS property, so .fadeTo(0, opacity) is the same as .css('opacity', opacity).
Additional Notes:
- All jQuery effects, including
.fadeTo(), can be turned off globally by settingjQuery.fx.off = true, which effectively sets the duration to 0. For more information, see jQuery.fx.off. - Because of the nature of
requestAnimationFrame(), you should never queue animations using asetIntervalorsetTimeoutloop. In order to preserve CPU resources, browsers that supportrequestAnimationFramewill not update animations when the window/tab is not displayed. If you continue to queue animations viasetIntervalorsetTimeoutwhile animation is paused, all of the queued animations will begin playing when the window/tab regains focus. To avoid this potential problem, use the callback of your last animation in the loop, or append a function to the elements.queue()to set the timeout to start the next animation.
Examples:
Example: Animates first paragraph to fade to an opacity of 0.33 (33%, about one third visible), completing the animation within 600 milliseconds.
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-1.7rc2.js"></script>
</head>
<body>
<p>
Click this paragraph to see it fade.
</p>
<p>
Compare to this one that won't fade.
</p>
<script>
$("p:first").click(function () {
$(this).fadeTo("slow", 0.33);
});
</script>
</body>
</html>Example: Fade div to a random opacity on each click, completing the animation within 200 milliseconds.
<!DOCTYPE html>
<html>
<head>
<style>
p { width:80px; margin:0; padding:5px; }
div { width:40px; height:40px; position:absolute; }
div#one { top:0; left:0; background:#f00; }
div#two { top:20px; left:20px; background:#0f0; }
div#three { top:40px; left:40px; background:#00f; }
</style>
<script src="http://code.jquery.com/jquery-1.7rc2.js"></script>
</head>
<body>
<p>And this is the library that John built...</p>
<div id="one"></div>
<div id="two"></div>
<div id="three"></div>
<script>
$("div").click(function () {
$(this).fadeTo("fast", Math.random());
});
</script>
</body>
</html>Example: Find the right answer! The fade will take 250 milliseconds and change various styles when it completes.
<!DOCTYPE html>
<html>
<head>
<style>
div, p { width:80px; height:40px; top:0; margin:0;
position:absolute; padding-top:8px; }
p { background:#fcc; text-align:center; }
div { background:blue; }
</style>
<script src="http://code.jquery.com/jquery-1.7rc2.js"></script>
</head>
<body>
<p>Wrong</p>
<div></div>
<p>Wrong</p>
<div></div>
<p>Right!</p>
<div></div>
<script>
var getPos = function (n) {
return (Math.floor(n) * 90) + "px";
};
$("p").each(function (n) {
var r = Math.floor(Math.random() * 3);
var tmp = $(this).text();
$(this).text($("p:eq(" + r + ")").text());
$("p:eq(" + r + ")").text(tmp);
$(this).css("left", getPos(n));
});
$("div").each(function (n) {
$(this).css("left", getPos(n));
})
.css("cursor", "pointer")
.click(function () {
$(this).fadeTo(250, 0.25, function () {
$(this).css("cursor", "")
.prev().css({"font-weight": "bolder",
"font-style": "italic"});
});
});
</script>
</body>
</html>