Starting an Animation From a Given Value

The YUI Animation Utility allows you to specify arbitrary starting values for your animations.

For this example, we will animate the width of the <div> element named demo.

Add a little style so that we can see the animation in action:

<style type="text/css"> #demo { background:#ccc; overflow:hidden; /* so we can animate to zero width */ width:200px; } </style>

Create the demo element and a button to run the animation:

<div id="demo">Demo</div> <button id="demo-run">run</button>

Now we create an instance of YAHOO.util.Anim, passing it the element we wish to animate, and the style attribute(s) to be animated. The from field is optional (will start from current value if omitted). In this case, we will start from 600:

<script type="text/javascript"> var attributes = { width: { from: 600, to: 0 } }; var anim = new YAHOO.util.Anim('demo', attributes); </script>

The final step is to call the animate method on our instance to start the animation. The button will be the trigger that begins the animation sequence:

<script type="text/javascript"> YAHOO.util.Event.on('demo-run', 'click', function() { anim.animate(); }); </script>

This is an example of customizing the starting animation value with YUI Animation Utility.