<link href="{{componentAssets}}/anim.css" rel="stylesheet" type="text/css">

<div class="intro">

<p>This demonstrates how to use the <code>reverse</code> attribute to change the behavior of the animation.</p>

<p> Click the icon in the header to toggle the element's <code>height</code>.</p>

</div>

<div class="example">

{{>reverse-source}}

</div>

<h2>Setting up the HTML</h2>

<p>First we add some HTML to animate.</p>

```

{{>reverse-source-html}}

```

<h2>Using the NodeFX Plugin</h2>

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

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

```

var module = Y.one('#demo');

// add fx plugin to module body

var content = module.one('.yui3-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

});

```

<h2>Creating the Control Element</h2>

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

```

// use dynamic control for dynamic behavior

var control = Y.Node.create(

'<a title="show/hide content" class="yui3-toggle">' +

'<em>toggle</em>' +

'</a>'

);

// append dynamic control to header section

module.one('.yui3-hd').appendChild(control);

```

<h2>Toggling Animation Behavior</h2>

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

```

var onClick = function(e) {

module.toggleClass('yui-closed');

content.fx.set('reverse', !content.fx.get('reverse')); // toggle reverse

};

```

<h2>Running the Animation</h2>

<p>Finally we add an event handler to run the animation.</p>

```

module.one('.yui3-toggle').on('click', onClick);

```

<h2>Complete Example Source</h2>

```

{{>reverse-source}}

```