container-query-polyfill: console error with class name ".container"

[peterschewe]

There is a strange bug with the container query polyfill.

This example...

.container {
  background: green;

  &--red {
    @include respond-below("md") {
      background: red;
    }
  }
}

...generates a console error

Uncaught (in promise) DOMException: Failed to execute 'querySelectorAll' on 'Document': '@media (max-width: 767px) ' is not a valid selector.
    at handleContainerProps (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:161:29)
    at transpileStyleSheet (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:126:7)
    at handleStyleTag (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:461:20)
    at http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:475:55
    at NodeList.forEach (<anonymous>)
    at init3 (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:475:38)
    at node_modules/container-query-polyfill/cqfill.js (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:543:7)
    at __init (http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:4:56)
    at http://localhost:1313/js/main.1a2445c7b5155a02bed583ff05508b038bd28e8d8b0aa8fb72f4ed43b3fdb7e2.js:861:33

It seems to be a combination of the class name (if the string container is included) and the SCSS Parent Selector (&--).

Findings from the debugging:

This works...

.container {
  background: green;

  &.red {
    @include respond-below("md") {
      background: red;
    }
  }

  &__red {
    @include respond-below("md") {
      background: red;
    }
  }
}

...and also this

.container2 {
  background: green;

  &--red {
    @include respond-below("md") {
      background: red;
    }
  }
}

[bezoerb]

This has something to do with the class name .container followed by a -
I think this line in the polyfill causing the error: https://github.com/GoogleChromeLabs/container-query-polyfill/blob/faf2600f7cd7b16e500f40676dd1b144005bd186/src/engine.ts#L291

Because of this error i needed to remove the .container styles in assets/scss/_base/base.scss in january.
We should add a hint in the js where the polyfill is initialized

[peterschewe]

I had wondered a few times where the .container styles had gone 😅

[psolbach]

This definitely caused us some headaches and in general I believe we should not include progressive polyfills per default, only those ensuring x browser compatibility.

[bezoerb]

https://github.com/GoogleChromeLabs/container-query-polyfill#browser-support

[bezoerb]

I'm fine with not including this by default but we should keep it around somewhere so that it's easy accessible in case someone needs to use it.

[bezoerb]

There's already a PR in place to fix this issue but the repository is kind of stale as the team is trying to rewrite the polyfill to match the latest spec and align with the web platform tests.

GoogleChromeLabs/container-query-polyfill#33