Features of image type input tags in HTML - Dave's Blog

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Features of image type input tags in HTML

2011 Nov 21, 11:00

A bug came up the other day involving markup containing <input type="image" src="http://example.com/.... I knew that "image" was a valid input type but it wasn't until that moment that I realized I didn't know what it did. Looking it up I found that it displays the specified image and when the user clicks on the image, the form is submitted with an additional two name value pairs: the x and y positions of the point at which the user clicked the image.

Take for example the following HTML:

<form action="http://example.com/">
<input type="image" name="foo" src="http://deletethis.net/dave/images/davebefore.jpg">
If the user clicks on the image, the browser will submit the form with a URI like the following:http://example.com/?foo.x=145&foo.y=124.

This seemed like an incredibly specific feature to be built directly into the language when this could instead be done with javascript. I looked a bit further and saw that its been in HTML since at least HTML2, which of course makes much more sense. Javascript barely existed at that point and sending off the user's click location in a form may have been the only way to do something interesting with that action.

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