YUI 3.x Home -

Site Search (YDN & YUIBlog):

# YUI Library Examples: Animation: Reversing an Animation

Note: This is YUI 3.x. Looking for YUI 2.x?

## Animation: Reversing an Animation

This demonstrates how to use the `reverse` attribute to change the behavior of the animation.

Click the icon in the header to toggle the element's `height`.

View example in new window.

#### Animation Demo

This an example of what you can do with the YUI Animation Utility.

Follow the instructions above to see the animation in action.

This is placeholder text used to demonstrate how the above animation affects subsequent content.

### Setting up the HTML

First we add some HTML to animate.

<div id="demo" class="yui-module"> <div class="yui-hd"> <h4>Animation Demo</h4> <a title="remove module" class="yui-toggle"><em>-</em></a> </div> <div class="yui-bd"> <p>This an example of what you can do with the YUI Animation Utility.</p> <p><em>Follow the instructions above to see the animation in action.</em></p> </div> </div>

### Using the NodeFX Plugin

For this example, we will use `Node`'s `fx` plugin to animate the element. The plugin adds the anim instance to the `Node` instance, pre-configuring it to use the Node instance as the `Anim`'s node. The `plug` method accepts a class to construct and an optional config to pass to the constructor.

Setting the `from` attribute to the expanded height of the element allows us to toggle the effect using the `reverse` attribute, which we will see below (`from` uses current value when omitted).

var module = Y.get('#demo'); // add fx plugin to module body var content = module.query('.yui-bd').plug(Y.Plugin.NodeFX, { from: { height: 0 }, to: { height: function(node) { // dynamic in case of change return node.get('scrollHeight'); // get expanded height (offsetHeight may be zero) } }, easing: Y.Easing.easeOut, from: { height: 0 }, duration: 0.5 });

### Creating the Control Element

Because our behavior only works when JS is available, let's go ahead and add our control element using JS as well.

// use dynamic control for dynamic behavior var control = Y.Node.create( '<a title="show/hide content" class="yui-toggle">' + '<em>toggle</em>' + '</a>' ); // append dynamic control to header section module.query('.yui-hd').appendChild(control);

### Toggling Animation Behavior

Before calling `run` in our `click` handler, we will use the `reverse` attribute toggle the direction of the animation depending on whether its opening or closing.

var onClick = function(e) { module.toggleClass('yui-closed'); content.fx.set('reverse', !content.fx.get('reverse')); // toggle reverse };

### Running the Animation

Finally we add an event handler to run the animation.

module.query('.yui-toggle').on('click', onClick);

### Full Script Source

YUI().use('anim', function(Y) { var module = Y.get('#demo'); // add fx plugin to module body var content = module.query('.yui-bd').plug(Y.Plugin.NodeFX, { from: { height: 0 }, to: { height: function(node) { // dynamic in case of change return node.get('scrollHeight'); // get expanded height (offsetHeight may be zero) } }, easing: Y.Easing.easeOut, duration: 0.5 }); var onClick = function(e) { module.toggleClass('yui-closed'); content.fx.set('reverse', !content.fx.get('reverse')); // toggle reverse content.fx.run(); }; // use dynamic control for dynamic behavior var control = Y.Node.create( '<a title="show/hide content" class="yui-toggle">' + '<em>toggle</em>' + '</a>' ); // append dynamic control to header section module.query('.yui-hd').appendChild(control); control.on('click', onClick); });

Copyright © 2009 Yahoo! Inc. All rights reserved.

Privacy Policy - Terms of Service - Copyright Policy - Job Openings