[whatwg] Ignore min and max if min > max

Ian Hickson ian at hixie.ch
Tue Jul 30 16:13:55 PDT 2013

On Wed, 17 Apr 2013, Mounir Lamouri wrote:
> Currently, the specification seems to take care of min > max by simply 
> making the element suffering from a value underflow such as a value 
> overflow. Also, <input type='range'> has a special behaviour in that 
> situation. However, if you try different implementations, the behaviours 
> when min > max a widely different and generally speaking, such context 
> can create pretty broken UI: a slider that can't move, a number spinner 
> that doesn't allow changing the number's value, etc.
> I believe that having a special behaviour when min > max would be 
> appropriate here. Basically, the min and max attributes should be 
> ignored in that situation. That means that the element's 'minimum' and 
> 'maximum' should be ignored in that situation unless there is a 'default 
> minimum' or a 'default maximum' (which would be used).
> Adding this to the specification would help having a decent fallback 
> when the attributes are broken instead of broken form controls.
> FWIW, Chrome's implementation of <input type='range'> seems to simply 
> ignore min and max when min > max. Opera doesn't show any UI in that 
> case.

Generally speaking, we define the behaviour when the markup is bogus, but 
we don't go out of our way to make it useful, for two main reasons: first, 
it's hard to tell what is useful when the information we have is known to 
be wrong (did they get them backwards? Did they omit a digit in the "max" 
value? Did they put the decimal in the wrong place on the "min" value?), 
and two, by having useful behaviour we make it much less likely that 
errors will be caught (it's easier to catch a bug if users can't enter any 
valid data at all, than it is if the error checking is just disabled).

Are we sure we really want to go down this path?

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

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