---
name: "CSS::Minifier::XS"
section: "3pm"
platform: "linux"
package: "libcss-minifier-xs-perl"
version: "0.13-1+b5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/CSS::Minifier::XS"
---

# CSS::Minifier::XS(3pm)

XS based CSS minifier

## NAME

CSS::Minifier::XS - XS based CSS minifier

## SYNOPSIS

```
  use CSS::Minifier::XS qw(minify);
  my $css      = '...';
  my $minified = minify($css);
```

## DESCRIPTION

`"CSS::Minifier::XS"` is a CSS "minifier"; its designed to remove unnecessary whitespace and comments from CSS files, while also **not** breaking the CSS.

`"CSS::Minifier::XS"` is similar in function to `"CSS::Minifier"`, but is substantially faster as its written in XS and not just pure Perl.

## METHODS

- minify($css)

  Minifies the given `$css`, returning the minified CSS back to the caller.

## HOW IT WORKS

`"CSS::Minifier::XS"` minifies the CSS by removing unnecessary whitespace from CSS documents.  Comment blocks are also removed, *except* when (a) they contain the word "copyright" in them, or (b) they're needed to implement the "Mac/IE Comment Hack".

Internally, the minification is done by taking multiple passes through the CSS document:

### Pass 1: Tokenize

First, we go through and parse the CSS document into a series of tokens internally.  The tokenizing process **does not** check to make sure that you've got syntactically valid CSS, it just breaks up the text into a stream of tokens suitable for processing by the subsequent stages.

### Pass 2: Collapse

We then march through the token list and collapse certain tokens down to their smallest possible representation.  *If* they're still included in the final results we only want to include them at their shortest.

- Whitespace

  Runs of multiple whitespace characters are reduced down to a single whitespace character.  If the whitespace contains any "end of line" (EOL) characters, then the end result is the *first* EOL character encountered.  Otherwise, the result is the first whitespace character in the run.

- Comments

  Comments implementing the "Mac/IE Comment Hack" are collapsed down to the smallest possible comment that would still implement the hack ("/\*\\\*/" to start the hack, and "/\*\*/" to end it).

- Zero Units

  Zero Units (e.g. `"0px"`) are reduced down to just "0", as the CSS specification indicates that the unit is not required when its a zero value.

### Pass 3: Pruning

We then go back through the token list and prune and remove unnecessary tokens.

- Whitespace

  Wherever possible, whitespace is removed; before+after comment blocks, and before+after various symbols/sigils.

- Comments

  Comments that either (a) are needed to implement the "Mac/IE Comment Hack", or that (b) contain the word "copyright" in them are preserved.  **All** other comments are removed.

- Symbols/Sigils

  Semi-colons that are immediately followed by a closing brace (e.g. ";}") are removed; semi-colons are needed to separate multiple declarations, but aren't required at the end of a group.

- Everything else

  We keep everything else; identifiers, quoted literal strings, symbols/sigils, etc.

### Pass 4: Re-assembly

Lastly, we go back through the token list and re-assemble it all back into a single CSS string, which is then returned back to the caller.

## AUTHOR

Graham TerMarsch (cpan@howlingfrog.com)

## COPYRIGHT

Copyright (C) 2007-, Graham TerMarsch.  All Rights Reserved.

This is free software; you can redistribute it and/or modify it under the same license as Perl itself.

## SEE ALSO

`"CSS::Minifier"`.