228174 - HTMLButtonElement.type should not be readonly to allow creation of differerent buttons with the DOM

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement, P2)

Description

[Martin Honnen]

The DOM Level 2 HTML specification states that the DOM type attribute (or
JavaScript property) of the HTMLButtonElement is readonly:
http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-34812697
However that is somehow nonsense as it means you can create a button dynamically
with
  var button = document.createElement('button');
but that you then cannot change the type of the button to for instance 'reset'
or 'button' to create one of the possible HTML button types and insert it into
the document.
I therefore suggest to make the DOM type attribute/property changeable.
If you look back at DOM Level 1 HTML then you will see that the DOM type
attribute of HTMLInputElement was specified as readonly too but of while
http://www.w3.org/TR/DOM-Level-2-HTML/changes.html
states
  the attribute type is no longer read only
The reason for that change was exactly the same problem as outlined above for
the HTMLButtonElement, as long as HTMLInputElement.type was readonly you
couldn't create the different input element types with the DOM (see
http://bugzilla.mozilla.org/show_bug.cgi?id=17544).
It would therefore be only consequential to make HTMLButtonElement.type to be
readable and writable too.
I will attach a test case that demonstrates that currently with Mozilla trying
to set HTMLButtonElement.type throws an execption causing any created button to
have the default type submit.
For completeness: tested with Mozilla 1.6b release build (Mozilla/5.0 (Windows;
U; Windows NT 5.1; en-US; rv:1.6b) Gecko/20031208) but that problems also occurs
with earlier versions.

Comment 1

[Martin Honnen]

Attachment: test case (all created buttons are of type submit as attempts to set HTMLButton.type throws an exception)

Comment 2

[Martin Honnen]

Attachment: workaround for HTMLButton.type readonly problem: Mozilla allows HTMLButtonElement.setAttribute('type', 'desired type value')

With Mozilla this is a workaround for the problem but I still think
HTMLButtonElement.type should not be readonly.

Comment 3

[Boris Zbarsky [:bzbarsky]]

jst, peterv, what do you think?  It would be pretty trivial to make this change,
I suspect; much easier than input types...  Should we push for an erratum to DOM2?

Comment 4

[Hixie (not reading bugmail)]

(I'd already made this change in the Web Forms draft, fwiw.)

Comment 5

[Johnny Stenback (:jst)]

I'd say let's make this change in Mozilla, but we can't change
nsIDOMHTMLButtonElement, it's frozen. We'll need to mark the readonly type
attribute in nsIDOMHTMLButtonElement as [noscript] (that change we can make
since it doesn't break binary compatibility) and add a writable type attribute
to nsIDOMNSHTMLButtonElement, that should do it.

Comment 6

[Boris Zbarsky [:bzbarsky]]

Attachment: So like this?

Passes the testcase in this bug....

Comment 7

[Boris Zbarsky [:bzbarsky]]

Taking.

Comment 8

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 138461 [details] [diff] [review]
So like this?

jst, would you review?

Comment 9

[Johnny Stenback (:jst)]

Comment on attachment 138461 [details] [diff] [review]
So like this?

Yeah, found a few nits to pick...

- In dom/public/idl/html/nsIDOMHTMLButtonElement.idl:

-  readonly attribute DOMString 	    type;
+  [noscript] readonly attribute DOMString  type;

Add a comment saying that there's a scriptable type attribute in
nsIDOMNSHTMLButtonElement.

- In dom/public/idl/html/nsIDOMNSHTMLButtonElement.idl:

+  attribute  DOMString      type;

Loose the extra space after 'attribute'.

r+sr=jst

Comment 10

[Boris Zbarsky [:bzbarsky]]

Attachment: With nits fixed

Comment 11

[Boris Zbarsky [:bzbarsky]]

Checked in for 1.7a.  Martin, thanks for bringing this up!