5 ms·

// I would love a two-forward-slashes comment in CSS

ajb92 5y ago
Me too. I expect though that there'd be lots of breaking changes around existing CSS having, for instance,`background-image: url(https://somedomain.abc/somefile.png https://somedomain.abc/somefile.png)`, as quotes are optional in URL values
- david422 5y ago
  // is only a comment if there is only whitespace directly before it?
  - mananaysiempre 5y ago
    Note that //foo/bar.txt is a valid address (a “network-path relative URI reference”[1]). Those are rarely seen but are used sometimes when the same resource or snippet needs to be usable with both HTTP and HTTPS. (I think I first learned about this form while reading a text on gradual migration to HTTPS circa 2014.) My impression is this form might actually be the original way of expressing network paths, what with UNC in Windows (\\server\share\file etc.) and POSIX carving out an exception specifically for two slashes at the beginning of a pathname (that is, foo//bar is the same as foo/bar and ///foo/bar is the same as /foo/bar, but //foo/bar may or may not be the same as /foo/bar). [1] https://datatracker.ietf.org/doc/html/rfc3986#section-4.2 https://datatracker.ietf.org/doc/html/rfc3986#section-4.2
    - chrismorgan 5y ago
      On the web, and most of the rest of the internet as well for most practical purposes, WHATWG’s URL Standard is now the normative reference for URLs, and obsoletes IETF’s RFC 3986 and 3987. (Source: https://url.spec.whatwg.org/#goals https://url.spec.whatwg.org/#goals.) There, this concept is called a scheme-relative URL (a much more sensible name): https://url.spec.whatwg.org/#scheme-relative-url-string https://url.spec.whatwg.org/#scheme-relative-url-string. They’re not the most common, but they’re not especially rare, either. HTML compressors especially will normally support emitting URLs in this form—you tell the compressor “this file you’re compressing will be served from the URL https://1.example/path/to/foo” https://1.example/path/to/foo” and it uses this knowledge to rewrite URLs inside the page, https://1.example/path/to/bar https://1.example/path/to/bar into bar, https://1.example/path/from https://1.example/path/from into ../from, https://1.example/baz https://1.example/baz into /baz, https://2.example/ https://2.example/ into //2.example, and http://1.example/ http://1.example/ into http://1.example http://1.example.
chrismorgan 5y ago
You kinda can: selector { //property: value; } This sets the property named "//property" to "value". Close enough. (Expressed otherwise: it’s approximately a comment until the next semicolon, barring quoted strings and parentheses.) //selector { property: value; } This is an invalid selector, and so the entire rule is ignored. (Expressed otherwise: it’s approximately a comment until the next opening curly brace’s matching closing curly brace.)
- zamadatix 5y ago
  Seems like it has plenty of disadvantages but no advantages to simply using the canonical method to do the same hack: /* // blah */ Edit: I mistakenly parsed this as using a dummy selector to hold the comment property, not just putting it inside real selectors.
  - galaxyLogic 5y ago
    It is faster to type // than /* ... */ . Any time you type the same character twice it is much faster than typing two separate characters. Further because I write a lot of JavaScript too I sometimes make the mistake of putting a // -comment into my CSS which breaks things. And when things break in CSS you usually don't get a clear error-message about it. It is always difficult to switch between two languages. I would prefer something like JavaScript stylesheets, if that was possible.
    - dylan604 5y ago
      Unless you are commenting out multiple lines/blocks of code.
      - galaxyLogic 5y ago
        True. But the IDE can of course help. In WebStorm I can select multiple lines of code and press Ctrl-/ to have them all turned into single-line comments if they were not, and uncomment them if they were. Single-line comments have the benefit that it is always clear to the reader which lines are comments. Whereas if you use multi-line comments to comment a large section of code it is no longer clear when reading it whether it is indeed "inside" a comment. And finally having both types of comments available is useful because you can multi-line-comment a section which already contains // -comments, whereas you can not multi-line comment a section which already contains multi-line comments.
nayuki 5y ago
I love it too, which is why I use Sass/SCSS, a gentle extension of CSS.
- frosted-flakes 5y ago
  I use SCSS for three reasons: // comments, nesting, and importing stylesheets. SCSS has so much more than that, but I don't use any of it.

Me too. I expect though that there'd be lots of breaking changes around existing CSS having, for instance,`background-image: url(https://somedomain.abc/somefile.png https://somedomain.abc/somefile.png)`, as quotes are optional in URL values

david422 5y ago
// is only a comment if there is only whitespace directly before it?
- mananaysiempre 5y ago
  Note that //foo/bar.txt is a valid address (a “network-path relative URI reference”[1]). Those are rarely seen but are used sometimes when the same resource or snippet needs to be usable with both HTTP and HTTPS. (I think I first learned about this form while reading a text on gradual migration to HTTPS circa 2014.) My impression is this form might actually be the original way of expressing network paths, what with UNC in Windows (\\server\share\file etc.) and POSIX carving out an exception specifically for two slashes at the beginning of a pathname (that is, foo//bar is the same as foo/bar and ///foo/bar is the same as /foo/bar, but //foo/bar may or may not be the same as /foo/bar). [1] https://datatracker.ietf.org/doc/html/rfc3986#section-4.2 https://datatracker.ietf.org/doc/html/rfc3986#section-4.2
  - chrismorgan 5y ago
    On the web, and most of the rest of the internet as well for most practical purposes, WHATWG’s URL Standard is now the normative reference for URLs, and obsoletes IETF’s RFC 3986 and 3987. (Source: https://url.spec.whatwg.org/#goals https://url.spec.whatwg.org/#goals.) There, this concept is called a scheme-relative URL (a much more sensible name): https://url.spec.whatwg.org/#scheme-relative-url-string https://url.spec.whatwg.org/#scheme-relative-url-string. They’re not the most common, but they’re not especially rare, either. HTML compressors especially will normally support emitting URLs in this form—you tell the compressor “this file you’re compressing will be served from the URL https://1.example/path/to/foo” https://1.example/path/to/foo” and it uses this knowledge to rewrite URLs inside the page, https://1.example/path/to/bar https://1.example/path/to/bar into bar, https://1.example/path/from https://1.example/path/from into ../from, https://1.example/baz https://1.example/baz into /baz, https://2.example/ https://2.example/ into //2.example, and http://1.example/ http://1.example/ into http://1.example http://1.example.

chrismorgan 5y ago

You kinda can: selector { //property: value; } This sets the property named "//property" to "value". Close enough. (Expressed otherwise: it’s approximately a comment until the next semicolon, barring quoted strings and parentheses.) //selector { property: value; } This is an invalid selector, and so the entire rule is ignored. (Expressed otherwise: it’s approximately a comment until the next opening curly brace’s matching closing curly brace.)

zamadatix 5y ago
Seems like it has plenty of disadvantages but no advantages to simply using the canonical method to do the same hack: /* // blah */ Edit: I mistakenly parsed this as using a dummy selector to hold the comment property, not just putting it inside real selectors.
- galaxyLogic 5y ago
  It is faster to type // than /* ... */ . Any time you type the same character twice it is much faster than typing two separate characters. Further because I write a lot of JavaScript too I sometimes make the mistake of putting a // -comment into my CSS which breaks things. And when things break in CSS you usually don't get a clear error-message about it. It is always difficult to switch between two languages. I would prefer something like JavaScript stylesheets, if that was possible.
  - dylan604 5y ago
    Unless you are commenting out multiple lines/blocks of code.
    - galaxyLogic 5y ago
      True. But the IDE can of course help. In WebStorm I can select multiple lines of code and press Ctrl-/ to have them all turned into single-line comments if they were not, and uncomment them if they were. Single-line comments have the benefit that it is always clear to the reader which lines are comments. Whereas if you use multi-line comments to comment a large section of code it is no longer clear when reading it whether it is indeed "inside" a comment. And finally having both types of comments available is useful because you can multi-line-comment a section which already contains // -comments, whereas you can not multi-line comment a section which already contains multi-line comments.

nayuki 5y ago

I love it too, which is why I use Sass/SCSS, a gentle extension of CSS.

frosted-flakes 5y ago
I use SCSS for three reasons: // comments, nesting, and importing stylesheets. SCSS has so much more than that, but I don't use any of it.