Hello. Thank you for the very useful plugin. In my case, however, I needed the ability to exclude certain selectors from receiving the prefix. I modified the code a bit and added an exclude option, which should be an array of RegExp's against which to test the selectors, before prepending anything:

...

var selectorExcluded = function (regexp) {
  return regexp.test(selector)
}

if (selector.startsWith(opts.selector.trim()) || opts.exclude.some(selectorExcluded)) {
  return selector
}

return opts.selector + selector

...

which could be used like:

require('postcss-prepend-selector')({ selector: '.my-stuff ', exclude: [/#content-wrapper/] })

It seems to be working, so I thought I'd share the idea in case you're interested in incorporating into the plugin.

Hi, thanks for this project, I was playing with it today and I think that is useful. However there are an issue related to the multiple selectors. For example:

.a , .b, .c{
}

The output is:

#prepend .a , .b, .c{
}

I took a look to the code and seems to be related to this line:

rule.selector = opts.selector + rule.selector;

We could validate this kind of selectors, Actually I don't know if postcss has an API to make this validation easier. Unfurtunately I don't have time to find the better solution. I'm sorry

Best Regards, Dariel

postcss-prepend-selector will prepend a selector to numerical values with decimal in keyframes

here is an exemple :

@keyframes fill-unfill-rotate {
  12.5% {
    -webkit-transform: rotate(135deg);
            transform: rotate(135deg);
  }
  25% {
    -webkit-transform: rotate(270deg);
            transform: rotate(270deg);
  }
}

prependSelector({selector:'.admin '}) will return :

@keyframes fill-unfill-rotate {
  .admin 12.5% {
    -webkit-transform: rotate(135deg);
            transform: rotate(135deg);
  }
  25% {
    -webkit-transform: rotate(270deg);
            transform: rotate(270deg);
  }
}

and CSS rules are broken