PHP Form Submission: Recognize Image Input Buttons
As you probably know, you can recognize a form submission from a "submit" input type by placing the following code in the "processing" PHP script:
if(isset($_POST['submit'])) { /* do stuff */ }
Did you know, however, that when using an "image" input type to submit the form, the above wont work? You need to add a "_x" to the field name in PHP:
if(isset($_POST['submit_x'])) { /* do stuff */ }
Odd, huh? This works the same when using a form "GET" method.
![From Webcam to Animated GIF: the Secret Behind chat.meatspac.es!]()
My team mate Edna Piranha is not only an awesome hacker; she's also a fantastic philosopher! Communication and online interactions is a subject that has kept her mind busy for a long time, and it has also resulted in a bunch of interesting experimental projects...
![5 HTML5 APIs You Didn’t Know Existed]()
When you say or read "HTML5", you half expect exotic dancers and unicorns to walk into the room to the tune of "I'm Sexy and I Know It." Can you blame us though? We watched the fundamental APIs stagnate for so long that a basic feature...
![HTML5 Placeholder Styling with CSS]()
Last week I showed you how you could style selected text with CSS. I've searched for more interesting CSS style properties and found another: INPUT placeholder styling. Let me show you how to style placeholder text within INPUTelements with some unique CSS code.
The CSS
Firefox...
![CSS Sprites]()
The idea of CSS sprites is pretty genius. For those of you who don't know the idea of a sprite, a sprite is basically multiple graphics compiled into one image. The advantages of using sprites are:
Fewer images for the browser to download, which means...
The _x and _y represent the coordinate location you clicked the image at.
Think this is only an issue with IE.
Yeah. The _x- and _y-coordinates are great for improving the security of a form! I’ve used this to determine if the form has been filled by a human. A spam-bot won’t submit any coordinates but a human has to click on the button and so there will always be coordinates (you’ll have to deactive submitting with the ENTER-button).
@Matthias: Good point on the security enhancement — I’ve never though of that!
@ Matthias
Thanks for posting your comment. I think telling the user that the ENTER button has been deactivated for bot protection is easier than having the user type in a captcha.
I’ll definitely be looking into that method and most likely incorporating it into my projects.
@Braxo – Wait – “Enter button” is deactivated? How would this affect someone who cannot use a mouse/relies on accessibility tools to fill out forms and the like?
Some sites cannot get away with it (coughtargetcough).
You can save yourself the trouble and just give the input a name attribute and check for that. Saves from changing code in two places (the input and the PHP submit validation).
<input type="image" src="image.png" name="submitted" value="Submit" />
I should clarify that…
It saves from changing code in 2 places should you want to change to/from an image submit or a standard submit.