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_____ _ _____ __ __ _____ _______
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/ ____| | |_ _| \/ |_ _|__ __|
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| (___ | | | | | \ / | | | | |
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\___ \| | | | | |\/| | | | | |
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____) | |____ _| |_| | | |_| |_ | |
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|_____/|______|_____|_| |_|_____| |_|
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==================================
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`SlimIt` is a JavaScript minifier written in Python.
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It compiles JavaScript into more compact code so that it downloads
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`SlimIt` also provides a library that includes a JavaScript parser,
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lexer, pretty printer and a tree visitor.
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`http://slimit.readthedocs.org/ <http://slimit.readthedocs.org/>`_
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$ [sudo] pip install slimit
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Or the bleeding edge version from the git master branch:
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$ [sudo] pip install git+https://github.com/rspivak/slimit.git#egg=slimit
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Let's minify some code
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----------------------
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From the command line:
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Usage: slimit [options] [input file]
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If no input file is provided STDIN is used by default.
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Minified JavaScript code is printed to STDOUT.
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-h, --help show this help message and exit
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-m, --mangle mangle names
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mangle top level scope (defaults to False)
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var foo = function( obj ) {
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for ( var name in obj ) {
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$ slimit --mangle < test.js
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var foo=function(a){for(var b in a)return false;return true;};
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>>> from slimit import minify
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... var foo = function( obj ) {
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... for ( var name in obj ) {
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>>> print minify(text, mangle=True, mangle_toplevel=True)
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var a=function(a){for(var b in a)return false;return true;};
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Iterate over, modify a JavaScript AST and pretty print it
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---------------------------------------------------------
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>>> from slimit.parser import Parser
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>>> from slimit.visitors import nodevisitor
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>>> from slimit import ast
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>>> tree = parser.parse('for(var i=0; i<10; i++) {var x=5+i;}')
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>>> for node in nodevisitor.visit(tree):
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... if isinstance(node, ast.Identifier) and node.value == 'i':
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... node.value = 'hello'
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>>> print tree.to_ecma() # print awesome javascript :)
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for (var hello = 0; hello < 10; hello++) {
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Writing custom node visitor
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---------------------------
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>>> from slimit.parser import Parser
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>>> from slimit.visitors.nodevisitor import ASTVisitor
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... "key1": "value1",
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>>> class MyVisitor(ASTVisitor):
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... def visit_Object(self, node):
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... """Visit object literal."""
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... for prop in node:
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... left, right = prop.left, prop.right
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... print 'Property key=%s, value=%s' % (left.value, right.value)
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... # visit all children in turn
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>>> parser = Parser()
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>>> tree = parser.parse(text)
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>>> visitor = MyVisitor()
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>>> visitor.visit(tree)
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Property key="key1", value="value1"
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Property key="key2", value="value2"
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Using lexer in your project
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---------------------------
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>>> from slimit.lexer import Lexer
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>>> lexer.input('a = 1;')
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>>> for token in lexer:
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LexToken(NUMBER,'1',1,4)
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LexToken(SEMI,';',1,5)
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You can get one token at a time using ``token`` method:
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>>> lexer.input('a = 1;')
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... token = lexer.token()
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LexToken(NUMBER,'1',1,4)
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LexToken(SEMI,';',1,5)
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`LexToken` instance has different attributes:
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>>> lexer.input('a = 1;')
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>>> token = lexer.token()
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>>> token.type, token.value, token.lineno, token.lexpos
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**SAM** - JQuery size after minification in bytes (the smaller number the better)
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+-------------------------------+------------+------------+------------+
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| Original jQuery 1.6.1 (bytes) | SlimIt SAM | rJSmin SAM | jsmin SAM |
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+===============================+============+============+============+
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| 234,995 | 94,290 | 134,215 | 134,819 |
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+-------------------------------+------------+------------+------------+
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- when doing name mangling handle cases with 'eval' and 'with'
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- foo["bar"] ==> foo.bar
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- consecutive declarations: var a = 10; var b = 20; ==> var a=10,b=20;
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- reduce simple constant expressions if the result takes less space:
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- IF statement optimizations
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1. if (foo) bar(); else baz(); ==> foo?bar():baz();
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2. if (!foo) bar(); else baz(); ==> foo?baz():bar();
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3. if (foo) bar(); ==> foo&&bar();
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4. if (!foo) bar(); ==> foo||bar();
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5. if (foo) return bar(); else return baz(); ==> return foo?bar():baz();
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6. if (foo) return bar(); else something(); ==> {if(foo)return bar();something()}
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- remove unreachable code that follows a return, throw, break or
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continue statement, except function/variable declarations
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- parsing speed improvements
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- The lexer and parser are built with `PLY <http://www.dabeaz.com/ply/>`_
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- Several test cases and regexes from `jslex <https://bitbucket.org/ned/jslex>`_
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- Some visitor ideas - `pycparser <http://code.google.com/p/pycparser/>`_
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- Many grammar rules are taken from `rkelly <https://github.com/tenderlove/rkelly>`_
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- Name mangling and different optimization ideas - `UglifyJS <https://github.com/mishoo/UglifyJS>`_
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- ASI implementation was inspired by `pyjsparser <http://bitbucket.org/mvantellingen/pyjsparser>`_
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The MIT License (MIT)
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README.rst
