Minify CSS using preg_replace

Question

I'm trying to minify multiple CSS files using preg_replace(). Actually, I'm only trying to remove any linebreaks/tabs and comments from the file. the following works for me:

$regex = array('{\t|\r|\n}', '{(/\*(.*?)\*/)}');
echo preg_replace($regex, '', file_get_contents($file));

But I'd like to do it in a single multiline regex, like this:

$regex = <<<EOF
{(
    \t
|
    \r
|
    \n
|
    /\*(.*?)\*/
)}x
EOF;
echo preg_replace($regex, '', file_get_contents($file));

However, this does not do anything at all. Is there any way to use a multiline regex like this? With the x flag, multiline expressions should work fine in PHP.

Better use a compression like deflate or gzip. That will give you better results. — Gumbo
– Gumbo, Commented Sep 4, 2009 at 13:53

Eddie · Accepted Answer · 2009-09-04 14:04:07Z

11

I'm not sure how you would do that, but here is a script my friend wrote that is pretty fast at minifying CSS:

function minimize_css($input)
{
    // Remove comments
    $output = preg_replace('#/\*.*?\*/#s', '', $input);
    // Remove whitespace
    $output = preg_replace('/\s*([{}|:;,])\s+/', '$1', $output);
    // Remove trailing whitespace at the start
    $output = preg_replace('/\s\s+(.*)/', '$1', $output);
    // Remove unnecesairy ;'s
    $output = str_replace(';}', '}', $output);
    return $output;
}

answered Sep 4, 2009 at 14:04

Eddie

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Karmic Coder · Accepted Answer · 2009-09-04 13:54:13Z

5

There are utilities available that may fit your needs and save you a potentially buggy regex.

The YUI compressor supports minification of CSS and javascript files.

You may wish to consider this or other existing options before writing your own.

answered Sep 4, 2009 at 13:54

Karmic Coder

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Comments

Cosmin · Accepted Answer · 2012-01-23 09:40:45Z

2

This is what I personally use for CSS:

$file_contents = file_get_contents($file);<br />
preg_replace('@({)\s+|(\;)\s+|/\*.+?\*\/|\R@is', '$1$2 ', $file_contents);

edited Jan 23, 2012 at 9:40

Cosmin

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answered Jul 8, 2011 at 20:26

Cornelius

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1 Comment

mickmackusa Over a year ago

Please explain which character in your pattern the regex engine is suppose to treat case-insensitively. There are two instances of unnecessary escaping in your pattern. Of course preg_replace() doesn't modify by reference, so it is misleading that the returned value is never used.

TylerH · Accepted Answer · 2024-01-29 14:52:03Z

0

function minifyCSS($css){
    $css = trim($css);
    $css = str_replace("\r\n", "\n", $css);
    $search = array("/\/\*[^!][\d\D]*?\*\/|\t+/","/\s+/", "/\}\s+/");
    $replace = array(null," ", "}\n");
    $css = preg_replace($search, $replace, $css);
    $search = array("/;[\s+]/","/[\s+];/","/\s+\{\\s+/", "/\\:\s+\\#/", "/,\s+/i", "/\\:\s+\\\'/i","/\\:\s+([0-9]+|[A-F]+)/i","/\{\\s+/","/;}/");
    $replace = array(";",";","{", ":#", ",", ":\'", ":$1","{","}");
    $css = preg_replace($search, $replace, $css);
    $css = str_replace("\n", null, $css);
    return $css;    
}

http://mhameen.blogspot.com/2010/04/crystal-script-manger-for-php.html#links

edited Jan 29, 2024 at 14:52

TylerH

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answered May 13, 2010 at 3:51

aminhotob

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1 Comment

TylerH Over a year ago

Your link is dead. Was this page where you found this code?

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