PostCSS should support optional charset parameter in inline sourcemaps

According to RFC2397 data:uri scheme may include optional charset parameter for text mime types.

Suppose, we have a generated file with unicode symbols and inlined sourcemap with a specified charset (we want to view it in Chrome DevTools). For example:

.test {
  content: 'привет';
}
/*# sourceMappingURL=data:application/json;charset=utf-8;base64,...*/

Right now if we try to use PostCSS with this file it fails with error:

Error: Unsupported source map encoding charset=utf-8;base64

I think PostCSS should consider optional charset (at least utf-8) and correctly apply previous sourcemap in this case.

[sydneyitguy]

I get an error with “Error: Unsupported source map encoding charset=utf8;base64” NOTE that utf8 instead of utf-8

Changed let utf64 = 'data:application/json;charset=utf-8;base64,'; line to let utf64 = 'data:application/json;charset=utf8;base64,';

temporarily fixed the issue. Do you think this is a common case?

[sydneyitguy]

@ai Ok just created https://github.com/postcss/postcss/issues/799