Question

Is it possible to write a regular expression which checks if a string (some code) is minified?

Many PHP/JS obfuscators remove white space chars (among other things).
So, the final minified code sometimes looks like this:

PHP:
$a=array();if(is_array($a)){echo'ok';}

JS:
a=[];if(typeof(a)=='object'&&(a instanceof Array){alert('ok')}

in both cases there are no space chars before and after “{“, “}”, “;”, etc. There also some other patterns which can help. I am not expecting a high accuracy regex, just need one which checks if at least 100 chars of string looks like minified code.
Thanks in advice.

PURPOSES: web malware scanner

Answer 1

I think a minifier will strip all newline characters, although there might possibly be one at the end of the file still if the minified code was pasted back in a text editor. Something like this will probably be fairly accurate:

/^[^\n\r]+(\r\n?|\n)?$/

That just tests that there are no newline characters in the whole thing except for possibly one at the end. So no guarantees, but I think it will work well on any longish block of code.