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Question about parsing with comments in selectors

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#64 3 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
javascript
Domain
frontend

Research direction

Start by running the example from the issue with postcss-js and inspect the resulting rule.selector and rule.selectors values. Compare that behavior with postcss-selector-parser's handling of comments and selector updates. Done means determining whether the reported comment form is supported and, if so, preserving the comment without splitting comma-containing comments into selector entries.

Written by the indexing model from the issue text.

Description

The Problem

First off I know this is a bit odd but, when parsing a selector with a comment before it PostCSS will treat it as a comment node. These can show up in IDEs (like VSCode for example) with information about the class. When using postcss-js the only way to do this, that I know of, is to add a comment to the selector itself. This seems to work okay-ish as long as the comment does not contain commas. If it does, any code relying on rule.selectors can break because it recieves pieces of a comment along with the other pieces of the selector.

Example Code

So, given the following:

import postcssJs from "postcss-js"
import postcss from "postcss"

const result = postcss().process({
  '/* this, is, a, test */ .test': {
     'color': 'blue'
  }
}, {
  parser: postcssJs,
}).sync()

console.log({
  selector: result.root.nodes[0].selector,
  selectors: result.root.nodes[0].selectors
})

You'll see that selector turns out to be: /* this, is, a, test */ .test instead of having a comment node before the rule.

The main problem though is that rule.selectors becomes an array with 4 items:

  • /* this
  • is
  • a
  • test */ .test

My Question

Is this something postcss-js is just not intended to support? If not, is there another possible solution? I noticed that postcss-selector-parser seems to handle comments in selectors fine — at least on some level. Though it doesn't clean out the selector of a rule when using updateSelector. I'd be happy to prep a PR that uses the selector parser to clean them but I have a feeling this might be a bit complicated because comments can technically appear in between parts of a selector which would require updating raws.

Dominant language
JavaScript
Stars
667
Forks
24
PR merge metrics
No merged PRs in 30d

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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