Preserve unit for some 0 values

[iamvdo]

There are bugs with some unitless 0.

For example, here are two examples with times (check in Chrome and Firefox to see differences)

http://jsbin.com/ledeb/2/edit
http://dabblet.com/gist/3746116

I think sand ms unit should be preserved, even with 0?

[thierryk]

As far as I know, 0 can be unit-less only for 'length' values.
time, degree, etc. need unit.

[hail2u]

In CSS Values and Units Module Level 3, 8.3. Attribute References: ‘attr()’, ‘length’ ‘angle’ ‘time’ ‘frequency’:

The default is ‘0’ in the relevant units, or else the property's minimum value if ‘0’ in the relevant units is not valid for the property.

and:

(e.g. positive lengths or angles from 0 to 90deg)

I think the spec suggests unit-less is not only for length unit.

[iamvdo]

The spec is pretty clear in 4.3.2 : (http://www.w3.org/TR/CSS2/syndata.html#values)

for zero lengths the unit identifier is optional

It doesn't appear anytime else in the whole spec.

I don't say that it won't work in browser. Just that it may be invalid to remove these units. :)

[thierryk]

Same in CSS3: 5. Distance Units: the <length> type

Lengths refer to distance measurements and are denoted by <length> in the property definitions. A length is a dimension. However, for zero lengths the unit identifier is optional (i.e. can be syntactically represented as the <number> ‘0’).

I may be wrong, but this:

A length is a dimension. However, for zero lengths the unit identifier is optional (i.e. can be syntactically represented as the <number> ‘0’).

seems to suggest that "even if length is a dimension, the unit identifier is optional". Meaning it is not the case for other dimensions. After all, 6. Other Units (angles, times, frequencies, resolutions) does not mention anything about using 0 without a unit identifier.

Fwiw, I did some digging and I found this article about <angle> on MDN where it says:

Note: 0 is not a valid angle value.

[stoyan]

hm, yes, I came across the MDN article so 0 angkles are preserved:
https://github.com/stoyan/cssshrink/blob/master/lib/visitors/zero-dimensions.js#L1

I'll add time always be 0s.

Not sure what to do about the others, some browser testing is in order

[stoyan]

btw, http://dabblet.com/gist/3746116 looks good in FF 30 Mac