.. copyright:
    Copyright 2011 - 2025
    André Malo or his licensors, as applicable

.. license:
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.


==============================
 rJSmin - Javascript Minifier
==============================

|**rJSmin**| is a javascript minifier written in python.

.. xxcontents::
    :local:


The minifier is based on the semantics of `jsmin.c by Douglas Crockford`_\.

The module is a re-implementation aiming for :doc:`speed <benchmark>`, so it
can be used at runtime (rather than during a preprocessing step). Usually it
produces the same results as the original ``jsmin.c``. It differs in the
following ways:

- there is no error detection: unterminated string, regex and comment
  literals are treated as regular javascript code and minified as such.
- Control characters inside string and regex literals are left untouched; they
  are not converted to spaces (nor to \\n)
- Newline characters are not allowed inside string and regex literals, except
  for line continuations in string literals (ECMA-5).
- "``return /regex/``" is recognized correctly.
- Line terminators after regex literals are handled more sensibly.
- More characters are allowed before regexes
- "``+ +``" and "``- -``" sequences are not collapsed to '``++``' or
  '``--``'
- Newlines before ``!`` operators are removed more sensibly
- (Unnested) template literals are supported
- Comments starting with an exclamation mark ('``!``') can be kept optionally
- |rJSmin| does not handle streams, but only complete strings. (However, the
  module provides a "streamy" interface).

Since most parts of the logic are handled by the regex engine it's way
faster than the original python port of ``jsmin.c`` by Baruch Even. The speed
factor varies between about 6 and 55 depending on input and python version
(it gets faster the more compressed the input already is). Compared to the
speed-refactored python port by Dave St.Germain the performance gain is less
dramatic but still between 3 and 50 (for huge inputs).

|rjsmin| comes with an optional C-reimplementation of the python/regex
implementation, which speeds up the minifying process even more.

Supported python versions are 2.7 and 3.6+.

.. _jsmin.c by Douglas Crockford: http://www.crockford.com/javascript/jsmin.c


Development Status
~~~~~~~~~~~~~~~~~~

|rjsmin| is stable.


Documentation
~~~~~~~~~~~~~

The module provides a simple function (generated apidoc below), called
``jsmin`` which takes the script as a string and returns the minified
script as a string.

The module additionally provides a "streamy" interface similar to the
one jsmin.c provides:

.. sourcecode:: console

    $ python -mrjsmin <script >minified

This command line interface takes two options:

  -b  Keep bang-comments (Comments starting with an exclamation mark)
  -p  Force using the python implementation (not the C implementation)


API Docs
--------

.. autofunction:: rjsmin.jsmin


License
~~~~~~~

|rjsmin| is available under the terms and conditions of the "Apache License,
Version 2.0." You'll find the detailed licensing terms in the root
directory of the source distribution package or online at
`http://www.apache.org/licenses/LICENSE-2.0
<http://www.apache.org/licenses/LICENSE-2.0>`_.


.. placeholder: Download


Bugs
~~~~

No bugs, of course. ;-)
But if you've found one or have an idea how to improve |rjsmin|, feel free
to send a pull request on `github <https://github.com/ndparker/rjsmin>`_
or send a mail to <rjsmin-bugs@perlig.de>.


Author Information
~~~~~~~~~~~~~~~~~~

|rjsmin| was written and is maintained by André Malo.


Acknowledgements
----------------

- `Douglas Crockford <http://www.crockford.com/>`_
- `Jeffrey Friedl <http://regex.info/>`_


Trivia / Fun
~~~~~~~~~~~~

|rJSmin| is a single pass substitution using a simple regular expression,
which looks like this:

.. sourcecode:: text

    pattern = (
        r'([^\047"\140/\000-\040]+)|((?:(?:\047[^\047\\\r\n]*(?:\\(?:[^'
        r'\r\n]|\r?\n|\r)[^\047\\\r\n]*)*\047)|(?:"[^"\\\r\n]*(?:\\(?:[^'
        r'\r\n]|\r?\n|\r)[^"\\\r\n]*)*")|(?:\140[^\140\\]*(?:\\(?:[^\r\n'
        r']|\r?\n|\r)[^\140\\]*)*\140))[^\047"\140/\000-\040]*)|(?<=[)])'
        r'(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+'
        r')*/))*(?:(?:(?://[^\r\n]*)?[\r\n])(?:[\000-\011\013\014\016-\0'
        r'40]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*)*((?:/(?![\r\n/*])[^/'
        r'\\\[\r\n]*(?:(?:\\[^\r\n]|(?:\[[^\\\]\r\n]*(?:\\[^\r\n][^\\\]'
        r'\r\n]*)*\]))[^/\\\[\r\n]*)*/[a-z]*))(?=(?:[\000-\011\013\014\0'
        r'16-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*(?:(?:(?://[^\r\n'
        r']*)?[\r\n])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^'
        r'/*][^*]*\*+)*/))*)*\.(?:[\000-\011\013\014\016-\040]|(?:/\*[^*'
        r']*\*+(?:[^/*][^*]*\*+)*/))*(?:(?:(?://[^\r\n]*)?[\r\n])(?:[\00'
        r'0-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*)'
        r'*[a-z])|(?<=[(,=:\[!&|?{};\r\n+*-])(?:[\000-\011\013\014\016-'
        r'\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*(?:(?:(?://[^\r\n]*)'
        r'?[\r\n])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*]'
        r'[^*]*\*+)*/))*)*((?:/(?![\r\n/*])[^/\\\[\r\n]*(?:(?:\\[^\r\n]|'
        r'(?:\[[^\\\]\r\n]*(?:\\[^\r\n][^\\\]\r\n]*)*\]))[^/\\\[\r\n]*)*'
        r'/[a-z]*))((?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/'
        r'*][^*]*\*+)*/))*(?:(?:(?://[^\r\n]*)?[\r\n])(?:[\000-\011\013'
        r'\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*)+(?=[^\000'
        r'-\040&)+,.:;=?\]|}-]))?|(?<=[\000-#%-,./:-@\[-^\140{-~-]return'
        r')(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*'
        r'+)*/))*(?:((?:(?://[^\r\n]*)?[\r\n]))(?:[\000-\011\013\014\016'
        r'-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*)*((?:/(?![\r\n/*])'
        r'[^/\\\[\r\n]*(?:(?:\\[^\r\n]|(?:\[[^\\\]\r\n]*(?:\\[^\r\n][^'
        r'\\\]\r\n]*)*\]))[^/\\\[\r\n]*)*/[a-z]*))((?:[\000-\011\013\014'
        r'\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*(?:(?:(?://[^\r'
        r'\n]*)?[\r\n])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:'
        r'[^/*][^*]*\*+)*/))*)+(?=[^\000-\040&)+,.:;=?\]|}-]))?|(?<=[^\0'
        r'00-!#%&(*,./:-@\[\\^{|~])(?:[\000-\011\013\014\016-\040]|(?:/'
        r'\*[^*]*\*+(?:[^/*][^*]*\*+)*/))*(?:((?:(?://[^\r\n]*)?[\r\n]))'
        r'(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+'
        r')*/))*)+(?=[^\000-\040"#%-\047)*,./:-@\\-^\140|-~])|(?<=[^\000'
        r'-#%-,./:-@\[-^\140{-~-])((?:[\000-\011\013\014\016-\040]|(?:/'
        r'\*[^*]*\*+(?:[^/*][^*]*\*+)*/)))+(?=[^\000-#%-,./:-@\[-^\140{-'
        r'~-])|(?<=\+)((?:[\000-\011\013\014\016-\040]|(?:/\*[^*]*\*+(?:'
        r'[^/*][^*]*\*+)*/)))+(?=\+)|(?<=-)((?:[\000-\011\013\014\016-\0'
        r'40]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/)))+(?=-)|(?:[\000-\011\0'
        r'13\014\016-\040]|(?:/\*[^*]*\*+(?:[^/*][^*]*\*+)*/))+|(?:(?:(?'
        r'://[^\r\n]*)?[\r\n])(?:[\000-\011\013\014\016-\040]|(?:/\*[^*]'
        r'*\*+(?:[^/*][^*]*\*+)*/))*)+'
    )


Related
~~~~~~~

- `CSS Minifier rCSSmin <http://opensource.perlig.de/rcssmin/>`_


.. vim: ft=rest tw=72
