In many cases, in order to beautify the form will change the submit button to use a picture instead. But if didn't pay attention to details will result in repeat submit form, causing some inexplicable errors, such as repeated injection such as database records.
we see the following form is a simple code:

  code is as follows:  


<Loginform form id="" name=" loginform "action=" http://game.bluesky.cn/login.php "method=" get ">
<The input name="name"/>
<Input type="image" SRC="http://www.jb51.net//web/login.gif" name="imagesubmit/>"
</form>

this code is correct, there will be no duplicate submissions. &other; <Input type=" Image" >Throughout the &; In fact and &other <Input type=" Submit" >Throughout the &; The effect is the same, a little pictures that will be executed the submit () operation.
but some people don't trust, add an onclick to image movement of gild the lily, code such as:

  code is as follows:  


<Loginform form id="" name=" loginform "action=" http://game.bluesky.cn/login.php "method=" get ">
<The input name="name"/>
<Input type="image" SRC="http://www.jb51.net//web/login.gif" name="imagesubmit/>"
</form>

now submit a picture button two times, repeat submitted. Its function is equivalent to:

  code is as follows:  


<Input type="SUBMIT" >

it is wrong of course.
if you must use the onclick event, use <Img> To replace <Input type=" Image" >Is can work normally, the following code:

  code is as follows:  


<Loginform form id="" name=" loginform "action=" http://game.bluesky.cn/login.php "method=" get ">
<The input name="name"/>
<Img SRC="http://www.jb51.net//web/login.gif" name="imagesubmit/>"
</form>

I am the gutter capsize problems, lead to the user login to submit the graphical verification code what is correct. Think, users have submitted twice, the second submit verification code also can right?
2. Image button how to prohibit duplicate submissions?

  code is as follows:  


<Input type="image" SRC="http://www.jb51.net//web/bt.gif" >

the button how to prohibit duplicate submissions? Solutions:

  code is as follows:  


<Input type="image" SRC="http://www.jb51.net//web/bt.gif" >

in this way can avoid image button repeatedly submitting
but now there are three such button together, I want to by one of the following, all three cannot be submitted again. Solutions:

  code is as follows:  


<Script language="javascript" >
the function test () {
the for (I=0; i the document. The getElementsByName (' t1 ') [I] disabled=true;
}
</script>
<The form name="f1" method="post" action="1. HTM" target="_blank" >
<Input type="image" name="t1" SRC="http://bbs.51js.com/images/standard/newtopic.gif" >
<Input type="image" name="t1" SRC="http://bbs.51js.com/images/standard/newtopic.gif" >
<Input type="image" name="t1" SRC="http://bbs.51js.com/images/standard/newtopic.gif" >
</form>

use the image to file there are two ways to form:
1. <Input type=" Image" src=http://www.jb51.net//web/" XXX. Gif" >
the picture automatically to submit Form Form to type=" Submit" If submitted prior to judgment, is tested using

  code is as follows:  


<Input type="image" SRC="http://www.jb51.net//web/xxx.gif" >

but commit occurs form is submitted in this way the phenomenon of two, often can create form elements are duplicate submissions, database are included in the abnormal!!!!!
especially with IE problem, use the firefox will not complain! Note that at this time, to put the database is set to the same information to the only!
the reason: in HTML a description of the image is &other Create an image control, the control will lead to form has been submitted immediately after click &throughout; .
2. <Img Alt=" Submit " src=http://www.jb51.net//web/" XXX. Gif" Id="art580">


This concludes the body part