Question

Why does my form submit twice?

Asked by: meverest

Hi Folks,

I have this form that submits twice for some crazy reason.  I just can't work out *why*.  The submit is done via an image button that fires a javascript function with onClick() event.

When I watch this action with fiddler tool, I see that the browser posts twice.  I can make it post just once if I remove the line

//document.login.submit();

but why does it submit at all?  I am assuming that 'image' form field behaves like 'button' - perhaps it realy behaves like 'submit' type?

Any clues will be gratefully accepted!

Thanks and regards,  Mike.

<script language="javascript">
var clicked = false;
function do_login()
{
	if (! clicked )
	{
		clicked = true;
		document.login.submit();
	}
	else return false;
}
</script>
 
<form name="login" action="http://login.host/login" method="post">
username: <input style="width: 240px" name="username" type="text" value="" /><br>
password: <input style="width: 240px" name="password" type="password" /><br>
<a onClick="return do_login()" target="_top" onMouseDown="" onMouseUp="">
<input type="image" name="loginbutt" src="templates/loginbutt.gif" alt="Log into system" value="LOGON">
</a>
</form>

                                  
1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:

Select allOpen in new window

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-02-08 at 19:26:51ID24124656
Topics

Scripting Languages

,

Web Development

,

WebApplications

Participating Experts
1
Points
500
Comments
7

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Disable pressing on a submit button twice
    I want to disable pressing on submit button after the form has been submited, so my command will not processed twice. When i use my 'inLoad' variable, the second press lock the current page in browser and the next page not reached. What can i do?
  2. Single SUBMIT button that behaves like Multiple SUBMITs
    Hello, Sorry if this question has been posted before. This is my first day working with Javascript. Right now I am developing the firmware for a embedded http server that runs on a PIC microprocessors. Due to the memory limitations of this device the maximum http string len...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: hieloPosted on 2009-02-08 at 19:34:12ID: 23587181

input type="image" IS a submit button. So you are submitting via the image and via the onclick on the "a" tag. Get rid of the "a" tag.

 

by: meverestPosted on 2009-02-08 at 19:39:34ID: 23587196

ahah,

>> input type="image" IS a submit button

OK, so i can get rid of the anchor tag, and put onClick="do_login()" for the image tag instead?

Cheers.

 

by: hieloPosted on 2009-02-08 at 19:50:18ID: 23587240

>>onClick="do_login()" for the image tag instead
Yes, but you don't need the onclick at all. The input type="image" will submit when clicked.

 

by: meverestPosted on 2009-02-08 at 19:57:09ID: 23587261

OK,

>> The input type="image" will submit when clicked.

yes, but I also want to prevent a double-click causing multiple submit events, so I am thinking that this would do it:

onClick="return do_login()"

how ironic that I wanted to prevent a double click to cause duplicate POST events, and ended up causing duplicate POST every time! ;-D

Cheers.

 

by: hieloPosted on 2009-02-08 at 20:27:09ID: 23587363

>>onClick="return do_login()"
OK, them make sure you return false in your function always.

function do_login()
{
        if (! clicked )
        {
                clicked = true;
                document.login.submit();
        }
return false;
}
 
when this is executed:
 document.login.submit();
 
the form will be submitted regardless of what's the return value. But if you return false always, you are making sure that the submission is NOT triggered by the input element, which is what you want since you are doing the submission via javascript.

                                              
1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:

Select allOpen in new window

 

by: meverestPosted on 2009-02-08 at 21:24:21ID: 23587561

OK, thanks!

This is what I have settled on.  I know that the 'return true;' is probably technically not required, but I figure that it is worth putting it in there for 'readability'.

Your assistance is very much appreciated!

Cheers.



function do_login()
{
        if (! clicked )
        {
                clicked = true;
                return true;
        }
return false;
}
 
<form name="login" action="http://login.host/login" method="post">
username: <input style="width: 240px" name="username" type="text" value="" /><br>
password: <input style="width: 240px" name="password" type="password" /><br>
<input onClick="return do_login()" type="image" name="loginbutt" src="templates/loginbutt.gif" alt="Log into system" value="LOGON">
</form>
                                              
1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:

Select allOpen in new window

 

by: meverestPosted on 2009-02-08 at 21:25:15ID: 31544386

Thanks!

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...