postcss-values-parser can't parse IE filter values, so need some way to pass through ignoreUnknownWords option

[jayandor]

If you write a CSS rule that looks like the following:

.thing {
  height: 100px;
  filter: alpha(opacity=80);
}

Or like this:

.thing {
  height: 100px;
  -ms-filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=80);
}

then postcss-values-parser gets caught on the values with the equal sign and fails. The obvious answer is just don't use these outdated values, but unfortunately I don't have an option as they're included in vital dependencies on my project.

I see that postcss-values-parser has an ignoreUnknownWords option for the parse() method, but I can't see any way in this module to pass it through. It would be great if either you could expose that option, or if you already know of some other way to get around the parsing issue.

[gavinmcfarland]

Good spot. Let me look at this weekend a d vet back to you.