Color transitions do not work when CSS comments are in the color strings

[gian-didom]

Expected behavior

when transitioning from this:

chart.data.dataset[0].backgroundColor = 'rgba(255,0,0, /*alpha*/ 0.5)

to this:

chart.data.dataset[0].backgroundColor = 'rgba(0,255,0, /*alpha*/ 0.5)

I would expect the transition to happen regardless of the comment in the /* */.

Current behavior

Despite the final colors being correctly applied, there is no transition between the color in any setting. Color transition happens instantly

Reproducible sample

https://codepen.io/Gianfry7/pen/qEddoZg

Optional extra steps/info to reproduce

Refer to the codepen for a sample.

Possible solution

I think the problem is in the default color interpolator which is not able to remove the commen, while the interpreter for the canvas does. One may regex away all the /* */ content when parsing the color.

Context

I incurred in this bug while trying to lazily apply border and background colors with a single settings for datasets.

chart.js version

latest

Browser name and version

No response

Link to your project

No response

[kurkle]

Why would you expect that a color string string can contain a comment block?

[gian-didom]

My use case was covered in the CodePen; however, I think that the notation is valid in CSS (or, at least, Chrome and Safari properly ignore comment blocks within color functions).

Or, at least, I would expect the color string to be as invalid at the beginning or end of transition.

[kurkle]

Inconsistency comes probably from the original string ending up to be the color at the ends of the transition. Not sure if that should be considered a bug or not.

[gian-didom]

I think it should be either unrecognized at the beginning and the ens as well, or have the comment ignored in order to allow the color mix.

It is a bit counterintuitive that two valid colors cannot be mixed together.

Personally, I spent a bit of time fiddling with animation settings, only to discover that it was caused by the color itself. It would have been easier if the color was not recognized from the beginning.