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Using JavaScript to handle drop-down list selections

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25 Jul 2009CPOL 1.3M   5K   31   21
A simple method of making dropdown lists automatically navigate to a new page when a new selection is made.

Introduction

We've all seen sites that feature drop down lists that automatically take you to your selection without you needing to make the cumbersome and lengthy step of hitting a "Go" button. If you've ever wondered how they do this then as you probably expected it's very simple.   

What on Earth am I talking about?

Picture a drop down list as follows:

Screenshot - dropdown.png

We often see a button next to the list that the user should press in order to actually activate there selection:

Screenshot - dropdown2.png

The user selects the value from the dropdown, hits Go, and the choice is made. By using javascript we can have the list notify us when a change is made, and we can essentially hit that Go button for the user. Not only do we save the use all the hassle of clicking on a button, we also get a handy reduction in the amount of screen real estate used.

How do we do it?

A typical dropdown list is instantiated using the following:

ASP.NET
<select name=select1>
<option>Value 1</option>
<option>Value 2</option>
<option>Value 3</option>
</select>

(Give or take some attributes). What we do is add an attribute that instructs the page to call our handler for when the list selection is changed.

ASP.NET
<select name=select1 onchange='OnChange(this.form.select1);'>

Our handler will look up the value that has just been selected, and navigate to an appropriate URL. An example of this is shown below:

ASP.NET
<SCRIPT LANGUAGE=javascript>
<!--
function OnChange(dropdown)
{
    var myindex  = dropdown.selectedIndex
    var SelValue = dropdown.options[myindex].value
    var baseURL  = <Some value based on SelValue>
    top.location.href = baseURL;
    
    return true;
}
//-->
</SCRIPT>

What if the user isn't using JavaScript?

We use the <noscript> tag to help us. We provide a Go button for the list, but only show it if JavaScript is not present:  

ASP.NET
<select name=select1>
<option>Value 1</option>
<option>Value 2</option>
<option>Value 3</option>
</select><noscript><INPUT type="submit" value="Go" name=submit1></noscript>

License

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


Written By
Founder CodeProject
Canada Canada
Chris Maunder is the co-founder of CodeProject and ContentLab.com, and has been a prominent figure in the software development community for nearly 30 years. Hailing from Australia, Chris has a background in Mathematics, Astrophysics, Environmental Engineering and Defence Research. His programming endeavours span everything from FORTRAN on Super Computers, C++/MFC on Windows, through to to high-load .NET web applications and Python AI applications on everything from macOS to a Raspberry Pi. Chris is a full-stack developer who is as comfortable with SQL as he is with CSS.

In the late 1990s, he and his business partner David Cunningham recognized the need for a platform that would facilitate knowledge-sharing among developers, leading to the establishment of CodeProject.com in 1999. Chris's expertise in programming and his passion for fostering a collaborative environment have played a pivotal role in the success of CodeProject.com. Over the years, the website has grown into a vibrant community where programmers worldwide can connect, exchange ideas, and find solutions to coding challenges. Chris is a prolific contributor to the developer community through his articles and tutorials, and his latest passion project, CodeProject.AI.

In addition to his work with CodeProject.com, Chris co-founded ContentLab and DeveloperMedia, two projects focussed on helping companies make their Software Projects a success. Chris's roles included Product Development, Content Creation, Client Satisfaction and Systems Automation.

Comments and Discussions

 
Questioncodes downloads Pin
siele6-Jul-12 22:07
siele6-Jul-12 22:07 
QuestionArticle dates Pin
DaveAuld31-Jan-12 4:53
professionalDaveAuld31-Jan-12 4:53 
AnswerRe: Article dates Pin
Chris Maunder31-Jan-12 5:41
cofounderChris Maunder31-Jan-12 5:41 
Generalbackground color change in List box Pin
vinothkumar_Dhakshinamoorthy28-Jan-10 3:25
vinothkumar_Dhakshinamoorthy28-Jan-10 3:25 
GeneralUsing JavaScript to handle drop-down list selections Pin
padolsky11-Aug-09 4:58
padolsky11-Aug-09 4:58 
Generaldrop down multiple select Pin
Lokesh Lal16-Jun-09 18:10
Lokesh Lal16-Jun-09 18:10 
GeneralRe: drop down multiple select Pin
Chris Maunder17-Jun-09 3:06
cofounderChris Maunder17-Jun-09 3:06 
GeneralRe: drop down multiple select Pin
Lokesh Lal18-Jun-09 6:51
Lokesh Lal18-Jun-09 6:51 
GeneralRe: drop down multiple select Pin
Chris Maunder18-Jun-09 6:51
cofounderChris Maunder18-Jun-09 6:51 
GeneralRe: drop down multiple select Pin
Lokesh Lal18-Jun-09 18:00
Lokesh Lal18-Jun-09 18:00 
QuestionRequest:Answer Pin
Gitanjali Dua18-Mar-07 22:41
Gitanjali Dua18-Mar-07 22:41 
Questiondropdown(javascript) Pin
Parul Chaudhary28-Jan-07 21:04
Parul Chaudhary28-Jan-07 21:04 
GeneralOpen/expand Dropdown by Script Pin
guruk12317-Oct-06 4:00
guruk12317-Oct-06 4:00 
GeneralRefresh/Update dropdown list options Pin
missyz17-Nov-04 7:23
missyz17-Nov-04 7:23 
Questionnot using asp? Pin
angel_girl30-Dec-03 22:10
angel_girl30-Dec-03 22:10 
GeneralUse of arrays Pin
12-May-02 0:59
suss12-May-02 0:59 
GeneralUse OnClick instead of OnChange Pin
Dee A. Crouch17-Oct-00 10:19
sussDee A. Crouch17-Oct-00 10:19 
GeneralRe: Use OnClick instead of OnChange Pin
Steven Gregg31-May-01 3:13
Steven Gregg31-May-01 3:13 
GeneralRe: Use OnClick instead of OnChange Pin
25-Oct-01 1:01
suss25-Oct-01 1:01 

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