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I am trying to cause a block to "pulsate" between 100% opacity and some partially transparent opacity. I want to do this with the functionality that is built into the jQuery core, if possible. I would rather not add a plugin to get this effect. Here is the code that i am trying to use:
$(document).ready(function() {
function pulsate() {
$("#pulsating-block").animate({opacity: 0.2}, 3000).animate({opacity: 1}, 3000, null, function() {pulsate()});
}
pulsate(); });
The problem is that each time the animation completes, it pauses for about a second before looping again. How can I keep it from pausing so that I get a smooth "pulsating" effect? (Note: the animation is exaggerated in this example to highlight the problem that I am having)
687
Perhaps your issue is with the "swing" easing function jQuery uses by default.
You might want to try the "linear" easing function instead:
$(document).ready(function() {
function pulsate() {
$("#pulsating-block").
animate({opacity: 0.2}, 3000, 'linear').
animate({opacity: 1}, 3000, 'linear', pulsate);
}
pulsate();
});
I've also coded up a small pulsate plugin that includes a "bounce" easing function that may be more to your liking. I should note that the plugin uses a continuous calculation to perform the animation, not two separate fade-in/fade-out animations, so it might help with the "pause" issue. (To be honest, I still don't see the pause you are talking about.)
http://jsbin.com/isicu (editable via http://jsbin.com/isicu/edit)
(function ($) {
$.fn.pulsate = function (properties, duration, type, speed, callback) {
type = type || 'Swing'
speed = speed || 'Normal';
this.animate(properties, duration, 'pulsate' + type + speed, callback);
};
function createPulsateLinear (speed) {
speed *= 2;
return function (p, n) {
return (Math.asin(Math.sin(Math.PI * n / speed)) + Math.PI / 2) / Math.PI;
}
}
function createPulsateSwing (speed) {
return function (p, n) {
return (1 + Math.sin(n / speed)) / 2;
}
}
function createPulsateBounce (speed) {
speed *= 2;
return function (p, n) {
return (
((Math.asin(Math.sin(Math.PI * n / speed)) + Math.PI / 2) / Math.PI) *
(Math.sin(Math.PI * n / speed) + 1) / -2 + 1
);
}
}
var speeds = {
fast: 100,
normal: 200,
slow: 400
}
$.extend(jQuery.easing, {
pulsateLinearFast: createPulsateLinear(speeds.fast),
pulsateLinearNormal: createPulsateLinear(speeds.normal),
pulsateLinearSlow: createPulsateLinear(speeds.slow),
pulsateSwingFast: createPulsateSwing(speeds.fast),
pulsateSwingNormal: createPulsateSwing(speeds.normal),
pulsateSwingSlow: createPulsateSwing(speeds.slow),
pulsateBounceFast: createPulsateBounce(speeds.fast),
pulsateBounceNormal: createPulsateBounce(speeds.normal),
pulsateBounceSlow: createPulsateBounce(speeds.slow)
});
})(jQuery);
$(document).ready(function() {
var
pulsatingBlocks = $('.pulsating-block'),
forever = 5 * 24 * 60 * 60 * 1000; // 5 days! (Which is forever in Internet time)
pulsatingBlocks.filter('.opacity').each(function () {
$(this).pulsate({opacity: 0.2}, forever, this.className.split(' ')[0], 'Slow');
});
pulsatingBlocks.filter('.top').each(function () {
$(this).pulsate({top: 100}, forever, this.className.split(' ')[0], 'Slow');
});
});
<!DOCTYPE html>
<html>
<head>
<script class="jsbin" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.js"></script>
<meta charset=utf-8 />
<title>Pulsate</title>
<style>
div { clear: left; margin-bottom: 2em; }
.pulsating-block {
width: 6em; height: 4em;
margin: 0.5em; margin-right: 10em;
float: left; clear: none; position: relative;
background: lightblue;
text-align: center;
padding-top: 2em;
font: bold 1em sans-serif;
}
</style>
</head>
<body>
<div>
<div class="Linear opacity pulsating-block">linear</div>
<div class="Swing opacity pulsating-block">swing</div>
<div class="Bounce opacity pulsating-block">bounce</div>
</div>
<div>
<div class="Linear top pulsating-block"></div>
<div class="Swing top pulsating-block"></div>
<div class="Bounce top pulsating-block"></div>
</div>
</body>
</html>
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