[whatwg] What it means for attributes of <input> to apply or not apply

Ian Hickson ian at hixie.ch
Thu Jan 12 17:42:43 PST 2012

On Wed, 22 Jun 2011, Edward O'Connor wrote:
> When adding the placeholder="" attribute to <input type=number>, one of 
> our engineers asked me about the behavior of content attributes that 
> don't apply to certain input types.
> Consider for example <input type=range>. The spec says "[t]he following 
> content attributes *must not be specified* and *do not apply* to the 
> element: […] placeholder[…]" (emphasis mine). The first bit ("must not 
> be specified") is clear: it's an authoring conformance requirement.
> The second bit ("does not apply to the element"), however, isn't clear. 
> Is it a UA conformance requirement? What does it mean? I *think* it 
> means that the placeholder="" attribute has no effect on the rendering 
> of <input type=range>. Does it also mean that the placeholder="" content 
> attribute shouldn't be reflected as an IDL attribute on <input> elements 
> of type=range? In Safari 5, Firefox 4, and Opera 11, placeholder="" gets 
> reflected as an IDL attribute, regardless of the value of type="".

On Wed, 22 Jun 2011, Aryeh Gregor wrote:
> It's reflected regardless of the type:
> http://www.whatwg.org/specs/web-apps/current-work/multipage/the-input-element.html#dom-input-placeholder
> "does not apply to the element" could use clarification, though.

On Thu, 23 Jun 2011, Ian Hickson wrote:
> It's a hook used here:
> http://www.whatwg.org/specs/web-apps/current-work/complete.html#common-input-element-attributes
> I'll add a hyperlink or something to make it clearer.

Now done. Let me know if it's still confusing.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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