ExtJS 4.2

HTML

<link rel="stylesheet" href="http://cdn.sencha.io/ext-4.2.0-gpl/resources/css/ext-all.css">

JavaScript

Ext.create('Ext.panel.Panel', {
    title: 'Accordion Layout',
    width: 300,
    height: 300,   
    layout: {
        type: 'accordion',      
        animate: true,
        multi: true,
    },
    items: [{
        hidden:true,        
    },{
        title: 'Panel 1',
        html: 'Panel content!',
        collapsed: true
    },{
        title: 'Panel 2',
        html: 'Panel content!',
        collapsed: true
    },{
        title: 'Panel 3',
        html: 'Panel content!',
        collapsed: true
    }],
    renderTo: Ext.getBody()
});