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Posted 28 Aug 2008

JavaScript Expandable / Collapsible Panel Control

, 21 Sep 2008
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This article describes how to create an Expandable / Collapsible Panel Control using JavaScript.


JavaScript Expandable / Collapsible Panel Control is a cross-browser JavaScript control.


Frankly speaking, I'm inspired to develop this control from the Microsoft Web site. If you surf the Microsoft Web site, then you will find a beautiful Panel Control at the right top corner of the default page. Some time ago, it had also smooth expand / collapse functionality but not now. In my Panel Control I've implemented this smooth expand / collapse functionality through JavaScript animation.


class.jpgPanel: It is a public cross-browser JavaScript class.


Panel Control has the following constructor:

  • Panel(Arguments): The constructor of the Panel class takes an argument of the type Object Literal. The definition of the argument Object Literal is given below:

    var Args = {
       Base: _Base, //Base reference where ListBox to be displayed.
       HeaderText: _ HeaderText, // Header Text.
       Width: _Width, // Width of the Control.
       ClickEventHandler: _ClickEventHandler // Reference of the click event handler. 


    var Args = {
       Base: document.getElementById('parent'),
       HeaderText: 'Items',
       Width: 200,
       ClickEventListener: OnClick

    In case you assign each Property of the argument Object Literal equal to null, then each property will acquire its default value.

    Properties and their default values have been tabulated below:

    PropertyDefault Value
    Base document.documentElement
    HeaderText Header Text
    Width 200
    ClickEventHandler Anonymous Method


Panel Control has the following public methods:

  • InsertItem(Text, Value): Used to insert an Panel Item. It takes two arguments:
    • Text: Item Text
    • Value: Item Value
  • GetItems(): Used to get collection of all Panel Items
  • GetItem(Index): Used to get a Panel Item at a given Item index. Returns null in case Item isn't found. It takes one argument:
    • Index: Item Index
  • RemoveItems(): Used to delete all the Panel Items. Returns number of Items deleted
  • RemoveItem(Index): Used to delete a Panel Item at a given Item index. Returns true on successful deletion, else false. It takes one argument
    • Index: Item Index
  • GetTotalItems(): Used to get total number of Panel Items
  • Contains(Index): Used to check whether a Panel Item exists at a given Item index or not. Returns true if Item exists, else false. It takes one argument:
    • Index: Item Index
  • Dispose(): Used to destroy Panel object

Note: The Panel Item is an Object Literal and has the following definition:

var PItem = {
   IsSelected: _IsSelected, // true/false.
   Text: _Text, // Item Text.
   Value: _Value, // Item Value.


Panel Control has only one property:

  • Version: Used to get the current version of the Panel Control


Panel Control has only one event:

  • Click: Fires when any one Panel Item is clicked

The local anonymous method that responds to the click event (i.e. event handler) has the following signature:

var EventHandler = function(Sender, EventArgs) {}

Here, Sender is the reference of the element (in this case, the Panel Item) that raises the click event and EventArgs is a Object Literal that contains necessary information regarding the event. EventArgs Object Literal has the following definition:

var EventArgs = {
   Text: _Text, // Item Text.
   Value: _Value, // Item Value.

Using the Control

Add the reference of the Panel.js file in your Web page:

<script type=&quot;text/javascript&quot; src=&quot;JS/Panel.js&quot;></script>

Create an div element in the Web page.

<div id=&quot;parent&quot;></div>

Now create a script tag in the head section of the Web page and put the following code in the window.onload event as:

<script type=&quot;text/javascript&quot;>
   var oPanel = null;
   window.onload = function()
       var Args = {
             Base: document.getElementById('parent'),
             HeaderText: 'Items',
            Width: 200,
            ClickEventListener: OnClick
       oPanel = new Panel(Args); 
       oPanel.InsertItem('MSDN', 'Insert');
       oPanel.InsertItem('HotMail', 'Delete');
       oPanel.InsertItem('Yahoo', 'Update');
       oPanel.InsertItem('Gmail', 'Cancel');
       oPanel.InsertItem('Rediff', 'Truncate');
       oPanel.InsertItem('AOL', 'Select');
       oPanel.InsertItem('Hi5', 'Between');
} </script>

In the above code, first an argument Object Literal with necessary properties has been created. Then Panel Control has been instantiated. Finally some Panel Items have been added to the Panel Object. Don't forget the click event handler wire up in the argument Object Literal as:

ClickEventListener: OnClick

Here, OnClick is the reference of the click event handler that is created as a local anonymous method:

var OnClick = function(Sender, EventArgs)


var OnClick = function(Sender, EventArgs)
   var Message = new Array();
   Message.push('Text: ' + EventArgs.Text);
   Message.push('Value: ' + EventArgs.Value);

   document.getElementById('DivMessage').innerHTML = Message.join('<br />');

The above method will get called whenever you click on any one Panel Item.

Invoke the Dispose method in the window.onunload event in order to destroy Panel Object as:

window.onunload = function(){ oPanel.Dispose(); }


So this is the approach that I have adopted to develop Expandable / Collapsible Panel Control through JavaScript. Please report bugs, errors and suggestions to improve this control.

Browser Compatibility

I have tested this Panel Control on a number of Web browsers:



This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Technical Lead Infogain India Pvt Ltd
India India

Samir NIGAM is a Microsoft Certified Professional. He is an insightful IT professional with results-driven comprehensive technical skill having rich, hands-on work experience n web-based applications using ASP.NET, C#, AJAX, Web Service, WCF, jQuery, Microsoft Enterprise Library , LINQ, MS Entity Framework, nHibernate, MS SQL Server & SSRS.

He has earned his master degree (MCA) from U.P. Technical University, Lucknow, INDIA, his post graduate dipoma (PGDCA ) from Institute of Engineering and Rural Technology, Allahabad, INDIA and his bachelor degree (BSc - Mathematics) from University of Allahabad, Allahabad, INDIA.

He has good knowledge of Object Oriented Programming, n-Tier Architecture, SOLID Principle, and Algorithm Analysis & Design as well as good command over cross-browser client side programming using JavaScript & jQuery,.


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Comments and Discussions

QuestionMy vote of 5 Pin
Filip D'haene8-Aug-11 4:52
memberFilip D'haene8-Aug-11 4:52 
GeneralCollapsible Panel : Expand and Collapse using Javascript in ASP.NET Pin
elizas10-Feb-10 0:32
groupelizas10-Feb-10 0:32 
GeneralWow...good job Pin
Oren Gatgno2-Jun-09 23:16
memberOren Gatgno2-Jun-09 23:16 
GeneralRe: Wow...good job Pin
Samir NIGAM2-Jun-09 23:29
mvpSamir NIGAM2-Jun-09 23:29 
GeneralThere is a bug in your new version yet!!! Pin
JLKEngine00822-Sep-08 17:32
memberJLKEngine00822-Sep-08 17:32 
Generalmore flexible Pin
ricardp18-Sep-08 3:28
memberricardp18-Sep-08 3:28 
GeneralRe: more flexible Pin
SAMir Nigam21-Sep-08 18:41
memberSAMir Nigam21-Sep-08 18:41 
QuestionHow can you modify the bug?? Pin
JLKEngine00817-Sep-08 18:25
memberJLKEngine00817-Sep-08 18:25 
GeneralThere is some bug!!! Pin
JLKEngine0086-Sep-08 16:29
memberJLKEngine0086-Sep-08 16:29 
GeneralTake a look at Pin
Member 6600955-Sep-08 8:22
memberMember 6600955-Sep-08 8:22 
GeneralRe: Take a look at Pin
The Wizard of Doze6-Sep-08 10:32
memberThe Wizard of Doze6-Sep-08 10:32 
GeneralGreat work! Pin
Helbrax5-Sep-08 2:11
memberHelbrax5-Sep-08 2:11 
GeneralRe: Great work! Pin
SAMir Nigam7-Sep-08 18:05
memberSAMir Nigam7-Sep-08 18:05 
AnswerRe: Great work! Pin
Helbrax8-Sep-08 1:59
memberHelbrax8-Sep-08 1:59 
GeneralOutstanding work Samir Nigam Pin
sarzzaidi4-Sep-08 23:41
membersarzzaidi4-Sep-08 23:41 
GeneralRe: Outstanding work Samir Nigam Pin
SAMir Nigam7-Sep-08 17:55
memberSAMir Nigam7-Sep-08 17:55 
Generalvery nice Pin
vegeta4ss3-Sep-08 6:26
membervegeta4ss3-Sep-08 6:26 
GeneralRe: very nice Pin
SAMir Nigam3-Sep-08 19:33
memberSAMir Nigam3-Sep-08 19:33 
GeneralVery Nice Article Pin
Sandeep Shekhar Upadhyay31-Aug-08 22:05
memberSandeep Shekhar Upadhyay31-Aug-08 22:05 
GeneralRe: Very Nice Article Pin
SAMir Nigam1-Sep-08 17:51
memberSAMir Nigam1-Sep-08 17:51 
Generalmind blowing Pin
san_geit31-Aug-08 20:25
membersan_geit31-Aug-08 20:25 
GeneralRe: mind blowing Pin
SAMir Nigam2-Sep-08 23:19
memberSAMir Nigam2-Sep-08 23:19 
Generalmind blowing!!! Pin
JHON HOVE30-Aug-08 0:51
memberJHON HOVE30-Aug-08 0:51 
GeneralRe: mind blowing!!! Pin
SAMir Nigam31-Aug-08 19:11
memberSAMir Nigam31-Aug-08 19:11 
GeneralNice Pin
steve_197030-Aug-08 0:49
membersteve_197030-Aug-08 0:49 

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