mirror of
https://github.com/seejohnrun/haste-server.git
synced 2024-11-01 11:31:22 +00:00
981 lines
39 KiB
HTML
981 lines
39 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml"
|
|
lang="en" xml:lang="en">
|
|
<head>
|
|
<title>UglifyJS – a JavaScript parser/compressor/beautifier</title>
|
|
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
|
|
<meta name="generator" content="Org-mode"/>
|
|
<meta name="generated" content="2011-12-09 14:59:08 EET"/>
|
|
<meta name="author" content="Mihai Bazon"/>
|
|
<meta name="description" content="a JavaScript parser/compressor/beautifier in JavaScript"/>
|
|
<meta name="keywords" content="javascript, js, parser, compiler, compressor, mangle, minify, minifier"/>
|
|
<style type="text/css">
|
|
<!--/*--><![CDATA[/*><!--*/
|
|
html { font-family: Times, serif; font-size: 12pt; }
|
|
.title { text-align: center; }
|
|
.todo { color: red; }
|
|
.done { color: green; }
|
|
.tag { background-color: #add8e6; font-weight:normal }
|
|
.target { }
|
|
.timestamp { color: #bebebe; }
|
|
.timestamp-kwd { color: #5f9ea0; }
|
|
.right {margin-left:auto; margin-right:0px; text-align:right;}
|
|
.left {margin-left:0px; margin-right:auto; text-align:left;}
|
|
.center {margin-left:auto; margin-right:auto; text-align:center;}
|
|
p.verse { margin-left: 3% }
|
|
pre {
|
|
border: 1pt solid #AEBDCC;
|
|
background-color: #F3F5F7;
|
|
padding: 5pt;
|
|
font-family: courier, monospace;
|
|
font-size: 90%;
|
|
overflow:auto;
|
|
}
|
|
table { border-collapse: collapse; }
|
|
td, th { vertical-align: top; }
|
|
th.right { text-align:center; }
|
|
th.left { text-align:center; }
|
|
th.center { text-align:center; }
|
|
td.right { text-align:right; }
|
|
td.left { text-align:left; }
|
|
td.center { text-align:center; }
|
|
dt { font-weight: bold; }
|
|
div.figure { padding: 0.5em; }
|
|
div.figure p { text-align: center; }
|
|
div.inlinetask {
|
|
padding:10px;
|
|
border:2px solid gray;
|
|
margin:10px;
|
|
background: #ffffcc;
|
|
}
|
|
textarea { overflow-x: auto; }
|
|
.linenr { font-size:smaller }
|
|
.code-highlighted {background-color:#ffff00;}
|
|
.org-info-js_info-navigation { border-style:none; }
|
|
#org-info-js_console-label { font-size:10px; font-weight:bold;
|
|
white-space:nowrap; }
|
|
.org-info-js_search-highlight {background-color:#ffff00; color:#000000;
|
|
font-weight:bold; }
|
|
/*]]>*/-->
|
|
</style>
|
|
<link rel="stylesheet" type="text/css" href="docstyle.css" />
|
|
<script type="text/javascript">
|
|
<!--/*--><![CDATA[/*><!--*/
|
|
function CodeHighlightOn(elem, id)
|
|
{
|
|
var target = document.getElementById(id);
|
|
if(null != target) {
|
|
elem.cacheClassElem = elem.className;
|
|
elem.cacheClassTarget = target.className;
|
|
target.className = "code-highlighted";
|
|
elem.className = "code-highlighted";
|
|
}
|
|
}
|
|
function CodeHighlightOff(elem, id)
|
|
{
|
|
var target = document.getElementById(id);
|
|
if(elem.cacheClassElem)
|
|
elem.className = elem.cacheClassElem;
|
|
if(elem.cacheClassTarget)
|
|
target.className = elem.cacheClassTarget;
|
|
}
|
|
/*]]>*///-->
|
|
</script>
|
|
|
|
</head>
|
|
<body>
|
|
|
|
<div id="preamble">
|
|
|
|
</div>
|
|
|
|
<div id="content">
|
|
<h1 class="title">UglifyJS – a JavaScript parser/compressor/beautifier</h1>
|
|
|
|
|
|
<div id="table-of-contents">
|
|
<h2>Table of Contents</h2>
|
|
<div id="text-table-of-contents">
|
|
<ul>
|
|
<li><a href="#sec-1">1 UglifyJS — a JavaScript parser/compressor/beautifier </a>
|
|
<ul>
|
|
<li><a href="#sec-1-1">1.1 Unsafe transformations </a>
|
|
<ul>
|
|
<li><a href="#sec-1-1-1">1.1.1 Calls involving the global Array constructor </a></li>
|
|
<li><a href="#sec-1-1-2">1.1.2 <code>obj.toString()</code> ==> <code>obj+“”</code> </a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#sec-1-2">1.2 Install (NPM) </a></li>
|
|
<li><a href="#sec-1-3">1.3 Install latest code from GitHub </a></li>
|
|
<li><a href="#sec-1-4">1.4 Usage </a>
|
|
<ul>
|
|
<li><a href="#sec-1-4-1">1.4.1 API </a></li>
|
|
<li><a href="#sec-1-4-2">1.4.2 Beautifier shortcoming – no more comments </a></li>
|
|
<li><a href="#sec-1-4-3">1.4.3 Use as a code pre-processor </a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#sec-1-5">1.5 Compression – how good is it? </a></li>
|
|
<li><a href="#sec-1-6">1.6 Bugs? </a></li>
|
|
<li><a href="#sec-1-7">1.7 Links </a></li>
|
|
<li><a href="#sec-1-8">1.8 License </a></li>
|
|
</ul>
|
|
</li>
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
<div id="outline-container-1" class="outline-2">
|
|
<h2 id="sec-1"><span class="section-number-2">1</span> UglifyJS — a JavaScript parser/compressor/beautifier </h2>
|
|
<div class="outline-text-2" id="text-1">
|
|
|
|
|
|
<p>
|
|
This package implements a general-purpose JavaScript
|
|
parser/compressor/beautifier toolkit. It is developed on <a href="http://nodejs.org/">NodeJS</a>, but it
|
|
should work on any JavaScript platform supporting the CommonJS module system
|
|
(and if your platform of choice doesn't support CommonJS, you can easily
|
|
implement it, or discard the <code>exports.*</code> lines from UglifyJS sources).
|
|
</p>
|
|
<p>
|
|
The tokenizer/parser generates an abstract syntax tree from JS code. You
|
|
can then traverse the AST to learn more about the code, or do various
|
|
manipulations on it. This part is implemented in <a href="../lib/parse-js.js">parse-js.js</a> and it's a
|
|
port to JavaScript of the excellent <a href="http://marijn.haverbeke.nl/parse-js/">parse-js</a> Common Lisp library from <a href="http://marijn.haverbeke.nl/">Marijn Haverbeke</a>.
|
|
</p>
|
|
<p>
|
|
( See <a href="http://github.com/mishoo/cl-uglify-js">cl-uglify-js</a> if you're looking for the Common Lisp version of
|
|
UglifyJS. )
|
|
</p>
|
|
<p>
|
|
The second part of this package, implemented in <a href="../lib/process.js">process.js</a>, inspects and
|
|
manipulates the AST generated by the parser to provide the following:
|
|
</p>
|
|
<ul>
|
|
<li>ability to re-generate JavaScript code from the AST. Optionally
|
|
indented—you can use this if you want to “beautify” a program that has
|
|
been compressed, so that you can inspect the source. But you can also run
|
|
our code generator to print out an AST without any whitespace, so you
|
|
achieve compression as well.
|
|
|
|
</li>
|
|
<li>shorten variable names (usually to single characters). Our mangler will
|
|
analyze the code and generate proper variable names, depending on scope
|
|
and usage, and is smart enough to deal with globals defined elsewhere, or
|
|
with <code>eval()</code> calls or <code>with{}</code> statements. In short, if <code>eval()</code> or
|
|
<code>with{}</code> are used in some scope, then all variables in that scope and any
|
|
variables in the parent scopes will remain unmangled, and any references
|
|
to such variables remain unmangled as well.
|
|
|
|
</li>
|
|
<li>various small optimizations that may lead to faster code but certainly
|
|
lead to smaller code. Where possible, we do the following:
|
|
|
|
<ul>
|
|
<li>foo["bar"] ==> foo.bar
|
|
|
|
</li>
|
|
<li>remove block brackets <code>{}</code>
|
|
|
|
</li>
|
|
<li>join consecutive var declarations:
|
|
var a = 10; var b = 20; ==> var a=10,b=20;
|
|
|
|
</li>
|
|
<li>resolve simple constant expressions: 1 +2 * 3 ==> 7. We only do the
|
|
replacement if the result occupies less bytes; for example 1/3 would
|
|
translate to 0.333333333333, so in this case we don't replace it.
|
|
|
|
</li>
|
|
<li>consecutive statements in blocks are merged into a sequence; in many
|
|
cases, this leaves blocks with a single statement, so then we can remove
|
|
the block brackets.
|
|
|
|
</li>
|
|
<li>various optimizations for IF statements:
|
|
|
|
<ul>
|
|
<li>if (foo) bar(); else baz(); ==> foo?bar():baz();
|
|
</li>
|
|
<li>if (!foo) bar(); else baz(); ==> foo?baz():bar();
|
|
</li>
|
|
<li>if (foo) bar(); ==> foo&&bar();
|
|
</li>
|
|
<li>if (!foo) bar(); ==> foo||bar();
|
|
</li>
|
|
<li>if (foo) return bar(); else return baz(); ==> return foo?bar():baz();
|
|
</li>
|
|
<li>if (foo) return bar(); else something(); ==> {if(foo)return bar();something()}
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
<li>remove some unreachable code and warn about it (code that follows a
|
|
<code>return</code>, <code>throw</code>, <code>break</code> or <code>continue</code> statement, except
|
|
function/variable declarations).
|
|
|
|
</li>
|
|
<li>act a limited version of a pre-processor (c.f. the pre-processor of
|
|
C/C++) to allow you to safely replace selected global symbols with
|
|
specified values. When combined with the optimisations above this can
|
|
make UglifyJS operate slightly more like a compilation process, in
|
|
that when certain symbols are replaced by constant values, entire code
|
|
blocks may be optimised away as unreachable.
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-1" class="outline-3">
|
|
<h3 id="sec-1-1"><span class="section-number-3">1.1</span> <span class="target">Unsafe transformations</span> </h3>
|
|
<div class="outline-text-3" id="text-1-1">
|
|
|
|
|
|
<p>
|
|
The following transformations can in theory break code, although they're
|
|
probably safe in most practical cases. To enable them you need to pass the
|
|
<code>--unsafe</code> flag.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-1-1" class="outline-4">
|
|
<h4 id="sec-1-1-1"><span class="section-number-4">1.1.1</span> Calls involving the global Array constructor </h4>
|
|
<div class="outline-text-4" id="text-1-1-1">
|
|
|
|
|
|
<p>
|
|
The following transformations occur:
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="src src-js"><span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3, 4) => [1,2,3,4]
|
|
Array(a, b, c) => [a,b,c]
|
|
<span class="org-keyword">new</span> <span class="org-type">Array</span>(5) => Array(5)
|
|
<span class="org-keyword">new</span> <span class="org-type">Array</span>(a) => Array(a)
|
|
</pre>
|
|
|
|
|
|
<p>
|
|
These are all safe if the Array name isn't redefined. JavaScript does allow
|
|
one to globally redefine Array (and pretty much everything, in fact) but I
|
|
personally don't see why would anyone do that.
|
|
</p>
|
|
<p>
|
|
UglifyJS does handle the case where Array is redefined locally, or even
|
|
globally but with a <code>function</code> or <code>var</code> declaration. Therefore, in the
|
|
following cases UglifyJS <b>doesn't touch</b> calls or instantiations of Array:
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="src src-js"><span class="org-comment-delimiter">// </span><span class="org-comment">case 1. globally declared variable</span>
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">Array</span>;
|
|
<span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3);
|
|
Array(a, b);
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">or (can be declared later)</span>
|
|
<span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3);
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">Array</span>;
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">or (can be a function)</span>
|
|
<span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3);
|
|
<span class="org-keyword">function</span> <span class="org-function-name">Array</span>() { ... }
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">case 2. declared in a function</span>
|
|
(<span class="org-keyword">function</span>(){
|
|
a = <span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3);
|
|
b = Array(5, 6);
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">Array</span>;
|
|
})();
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">or</span>
|
|
(<span class="org-keyword">function</span>(<span class="org-variable-name">Array</span>){
|
|
<span class="org-keyword">return</span> Array(5, 6, 7);
|
|
})();
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">or</span>
|
|
(<span class="org-keyword">function</span>(){
|
|
<span class="org-keyword">return</span> <span class="org-keyword">new</span> <span class="org-type">Array</span>(1, 2, 3, 4);
|
|
<span class="org-keyword">function</span> <span class="org-function-name">Array</span>() { ... }
|
|
})();
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">etc.</span>
|
|
</pre>
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-1-2" class="outline-4">
|
|
<h4 id="sec-1-1-2"><span class="section-number-4">1.1.2</span> <code>obj.toString()</code> ==> <code>obj+“”</code> </h4>
|
|
<div class="outline-text-4" id="text-1-1-2">
|
|
|
|
|
|
</div>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-2" class="outline-3">
|
|
<h3 id="sec-1-2"><span class="section-number-3">1.2</span> Install (NPM) </h3>
|
|
<div class="outline-text-3" id="text-1-2">
|
|
|
|
|
|
<p>
|
|
UglifyJS is now available through NPM — <code>npm install uglify-js</code> should do
|
|
the job.
|
|
</p>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-3" class="outline-3">
|
|
<h3 id="sec-1-3"><span class="section-number-3">1.3</span> Install latest code from GitHub </h3>
|
|
<div class="outline-text-3" id="text-1-3">
|
|
|
|
|
|
|
|
|
|
|
|
<pre class="src src-sh"><span class="org-comment-delimiter">## </span><span class="org-comment">clone the repository</span>
|
|
mkdir -p /where/you/wanna/put/it
|
|
<span class="org-builtin">cd</span> /where/you/wanna/put/it
|
|
git clone git://github.com/mishoo/UglifyJS.git
|
|
|
|
<span class="org-comment-delimiter">## </span><span class="org-comment">make the module available to Node</span>
|
|
mkdir -p ~/.node_libraries/
|
|
<span class="org-builtin">cd</span> ~/.node_libraries/
|
|
ln -s /where/you/wanna/put/it/UglifyJS/uglify-js.js
|
|
|
|
<span class="org-comment-delimiter">## </span><span class="org-comment">and if you want the CLI script too:</span>
|
|
mkdir -p ~/bin
|
|
<span class="org-builtin">cd</span> ~/bin
|
|
ln -s /where/you/wanna/put/it/UglifyJS/bin/uglifyjs
|
|
<span class="org-comment-delimiter"># </span><span class="org-comment">(then add ~/bin to your $PATH if it's not there already)</span>
|
|
</pre>
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-4" class="outline-3">
|
|
<h3 id="sec-1-4"><span class="section-number-3">1.4</span> Usage </h3>
|
|
<div class="outline-text-3" id="text-1-4">
|
|
|
|
|
|
<p>
|
|
There is a command-line tool that exposes the functionality of this library
|
|
for your shell-scripting needs:
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="src src-sh">uglifyjs [ options... ] [ filename ]
|
|
</pre>
|
|
|
|
|
|
<p>
|
|
<code>filename</code> should be the last argument and should name the file from which
|
|
to read the JavaScript code. If you don't specify it, it will read code
|
|
from STDIN.
|
|
</p>
|
|
<p>
|
|
Supported options:
|
|
</p>
|
|
<ul>
|
|
<li><code>-b</code> or <code>--beautify</code> — output indented code; when passed, additional
|
|
options control the beautifier:
|
|
|
|
<ul>
|
|
<li><code>-i N</code> or <code>--indent N</code> — indentation level (number of spaces)
|
|
|
|
</li>
|
|
<li><code>-q</code> or <code>--quote-keys</code> — quote keys in literal objects (by default,
|
|
only keys that cannot be identifier names will be quotes).
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
<li><code>--ascii</code> — pass this argument to encode non-ASCII characters as
|
|
<code>\uXXXX</code> sequences. By default UglifyJS won't bother to do it and will
|
|
output Unicode characters instead. (the output is always encoded in UTF8,
|
|
but if you pass this option you'll only get ASCII).
|
|
|
|
</li>
|
|
<li><code>-nm</code> or <code>--no-mangle</code> — don't mangle names.
|
|
|
|
</li>
|
|
<li><code>-nmf</code> or <code>--no-mangle-functions</code> – in case you want to mangle variable
|
|
names, but not touch function names.
|
|
|
|
</li>
|
|
<li><code>-ns</code> or <code>--no-squeeze</code> — don't call <code>ast_squeeze()</code> (which does various
|
|
optimizations that result in smaller, less readable code).
|
|
|
|
</li>
|
|
<li><code>-mt</code> or <code>--mangle-toplevel</code> — mangle names in the toplevel scope too
|
|
(by default we don't do this).
|
|
|
|
</li>
|
|
<li><code>--no-seqs</code> — when <code>ast_squeeze()</code> is called (thus, unless you pass
|
|
<code>--no-squeeze</code>) it will reduce consecutive statements in blocks into a
|
|
sequence. For example, "a = 10; b = 20; foo();" will be written as
|
|
"a=10,b=20,foo();". In various occasions, this allows us to discard the
|
|
block brackets (since the block becomes a single statement). This is ON
|
|
by default because it seems safe and saves a few hundred bytes on some
|
|
libs that I tested it on, but pass <code>--no-seqs</code> to disable it.
|
|
|
|
</li>
|
|
<li><code>--no-dead-code</code> — by default, UglifyJS will remove code that is
|
|
obviously unreachable (code that follows a <code>return</code>, <code>throw</code>, <code>break</code> or
|
|
<code>continue</code> statement and is not a function/variable declaration). Pass
|
|
this option to disable this optimization.
|
|
|
|
</li>
|
|
<li><code>-nc</code> or <code>--no-copyright</code> — by default, <code>uglifyjs</code> will keep the initial
|
|
comment tokens in the generated code (assumed to be copyright information
|
|
etc.). If you pass this it will discard it.
|
|
|
|
</li>
|
|
<li><code>-o filename</code> or <code>--output filename</code> — put the result in <code>filename</code>. If
|
|
this isn't given, the result goes to standard output (or see next one).
|
|
|
|
</li>
|
|
<li><code>--overwrite</code> — if the code is read from a file (not from STDIN) and you
|
|
pass <code>--overwrite</code> then the output will be written in the same file.
|
|
|
|
</li>
|
|
<li><code>--ast</code> — pass this if you want to get the Abstract Syntax Tree instead
|
|
of JavaScript as output. Useful for debugging or learning more about the
|
|
internals.
|
|
|
|
</li>
|
|
<li><code>-v</code> or <code>--verbose</code> — output some notes on STDERR (for now just how long
|
|
each operation takes).
|
|
|
|
</li>
|
|
<li><code>-d SYMBOL[=VALUE]</code> or <code>--define SYMBOL[=VALUE]</code> — will replace
|
|
all instances of the specified symbol where used as an identifier
|
|
(except where symbol has properly declared by a var declaration or
|
|
use as function parameter or similar) with the specified value. This
|
|
argument may be specified multiple times to define multiple
|
|
symbols - if no value is specified the symbol will be replaced with
|
|
the value <code>true</code>, or you can specify a numeric value (such as
|
|
<code>1024</code>), a quoted string value (such as ="object"= or
|
|
='https://github.com'<code>), or the name of another symbol or keyword (such as =null</code> or <code>document</code>).
|
|
This allows you, for example, to assign meaningful names to key
|
|
constant values but discard the symbolic names in the uglified
|
|
version for brevity/efficiency, or when used wth care, allows
|
|
UglifyJS to operate as a form of <b>conditional compilation</b>
|
|
whereby defining appropriate values may, by dint of the constant
|
|
folding and dead code removal features above, remove entire
|
|
superfluous code blocks (e.g. completely remove instrumentation or
|
|
trace code for production use).
|
|
Where string values are being defined, the handling of quotes are
|
|
likely to be subject to the specifics of your command shell
|
|
environment, so you may need to experiment with quoting styles
|
|
depending on your platform, or you may find the option
|
|
<code>--define-from-module</code> more suitable for use.
|
|
|
|
</li>
|
|
<li><code>-define-from-module SOMEMODULE</code> — will load the named module (as
|
|
per the NodeJS <code>require()</code> function) and iterate all the exported
|
|
properties of the module defining them as symbol names to be defined
|
|
(as if by the <code>--define</code> option) per the name of each property
|
|
(i.e. without the module name prefix) and given the value of the
|
|
property. This is a much easier way to handle and document groups of
|
|
symbols to be defined rather than a large number of <code>--define</code>
|
|
options.
|
|
|
|
</li>
|
|
<li><code>--unsafe</code> — enable other additional optimizations that are known to be
|
|
unsafe in some contrived situations, but could still be generally useful.
|
|
For now only these:
|
|
|
|
<ul>
|
|
<li>foo.toString() ==> foo+""
|
|
</li>
|
|
<li>new Array(x,…) ==> [x,…]
|
|
</li>
|
|
<li>new Array(x) ==> Array(x)
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
<li><code>--max-line-len</code> (default 32K characters) — add a newline after around
|
|
32K characters. I've seen both FF and Chrome croak when all the code was
|
|
on a single line of around 670K. Pass –max-line-len 0 to disable this
|
|
safety feature.
|
|
|
|
</li>
|
|
<li><code>--reserved-names</code> — some libraries rely on certain names to be used, as
|
|
pointed out in issue #92 and #81, so this option allow you to exclude such
|
|
names from the mangler. For example, to keep names <code>require</code> and <code>$super</code>
|
|
intact you'd specify –reserved-names "require,$super".
|
|
|
|
</li>
|
|
<li><code>--inline-script</code> – when you want to include the output literally in an
|
|
HTML <code><script></code> tag you can use this option to prevent <code></script</code> from
|
|
showing up in the output.
|
|
|
|
</li>
|
|
<li><code>--lift-vars</code> – when you pass this, UglifyJS will apply the following
|
|
transformations (see the notes in API, <code>ast_lift_variables</code>):
|
|
|
|
<ul>
|
|
<li>put all <code>var</code> declarations at the start of the scope
|
|
</li>
|
|
<li>make sure a variable is declared only once
|
|
</li>
|
|
<li>discard unused function arguments
|
|
</li>
|
|
<li>discard unused inner (named) functions
|
|
</li>
|
|
<li>finally, try to merge assignments into that one <code>var</code> declaration, if
|
|
possible.
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-4-1" class="outline-4">
|
|
<h4 id="sec-1-4-1"><span class="section-number-4">1.4.1</span> API </h4>
|
|
<div class="outline-text-4" id="text-1-4-1">
|
|
|
|
|
|
<p>
|
|
To use the library from JavaScript, you'd do the following (example for
|
|
NodeJS):
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="src src-js"><span class="org-keyword">var</span> <span class="org-variable-name">jsp</span> = require(<span class="org-string">"uglify-js"</span>).parser;
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">pro</span> = require(<span class="org-string">"uglify-js"</span>).uglify;
|
|
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">orig_code</span> = <span class="org-string">"... JS code here"</span>;
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">ast</span> = jsp.parse(orig_code); <span class="org-comment-delimiter">// </span><span class="org-comment">parse code and get the initial AST</span>
|
|
ast = pro.ast_mangle(ast); <span class="org-comment-delimiter">// </span><span class="org-comment">get a new AST with mangled names</span>
|
|
ast = pro.ast_squeeze(ast); <span class="org-comment-delimiter">// </span><span class="org-comment">get an AST with compression optimizations</span>
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">final_code</span> = pro.gen_code(ast); <span class="org-comment-delimiter">// </span><span class="org-comment">compressed code here</span>
|
|
</pre>
|
|
|
|
|
|
<p>
|
|
The above performs the full compression that is possible right now. As you
|
|
can see, there are a sequence of steps which you can apply. For example if
|
|
you want compressed output but for some reason you don't want to mangle
|
|
variable names, you would simply skip the line that calls
|
|
<code>pro.ast_mangle(ast)</code>.
|
|
</p>
|
|
<p>
|
|
Some of these functions take optional arguments. Here's a description:
|
|
</p>
|
|
<ul>
|
|
<li><code>jsp.parse(code, strict_semicolons)</code> – parses JS code and returns an AST.
|
|
<code>strict_semicolons</code> is optional and defaults to <code>false</code>. If you pass
|
|
<code>true</code> then the parser will throw an error when it expects a semicolon and
|
|
it doesn't find it. For most JS code you don't want that, but it's useful
|
|
if you want to strictly sanitize your code.
|
|
|
|
</li>
|
|
<li><code>pro.ast_lift_variables(ast)</code> – merge and move <code>var</code> declarations to the
|
|
scop of the scope; discard unused function arguments or variables; discard
|
|
unused (named) inner functions. It also tries to merge assignments
|
|
following the <code>var</code> declaration into it.
|
|
|
|
<p>
|
|
If your code is very hand-optimized concerning <code>var</code> declarations, this
|
|
lifting variable declarations might actually increase size. For me it
|
|
helps out. On jQuery it adds 865 bytes (243 after gzip). YMMV. Also
|
|
note that (since it's not enabled by default) this operation isn't yet
|
|
heavily tested (please report if you find issues!).
|
|
</p>
|
|
<p>
|
|
Note that although it might increase the image size (on jQuery it gains
|
|
865 bytes, 243 after gzip) it's technically more correct: in certain
|
|
situations, dead code removal might drop variable declarations, which
|
|
would not happen if the variables are lifted in advance.
|
|
</p>
|
|
<p>
|
|
Here's an example of what it does:
|
|
</p></li>
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
|
|
<pre class="src src-js"><span class="org-keyword">function</span> <span class="org-function-name">f</span>(<span class="org-variable-name">a</span>, <span class="org-variable-name">b</span>, <span class="org-variable-name">c</span>, <span class="org-variable-name">d</span>, <span class="org-variable-name">e</span>) {
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">q</span>;
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">w</span>;
|
|
w = 10;
|
|
q = 20;
|
|
<span class="org-keyword">for</span> (<span class="org-keyword">var</span> <span class="org-variable-name">i</span> = 1; i < 10; ++i) {
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">boo</span> = foo(a);
|
|
}
|
|
<span class="org-keyword">for</span> (<span class="org-keyword">var</span> <span class="org-variable-name">i</span> = 0; i < 1; ++i) {
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">boo</span> = bar(c);
|
|
}
|
|
<span class="org-keyword">function</span> <span class="org-function-name">foo</span>(){ ... }
|
|
<span class="org-keyword">function</span> <span class="org-function-name">bar</span>(){ ... }
|
|
<span class="org-keyword">function</span> <span class="org-function-name">baz</span>(){ ... }
|
|
}
|
|
|
|
<span class="org-comment-delimiter">// </span><span class="org-comment">transforms into ==></span>
|
|
|
|
<span class="org-keyword">function</span> <span class="org-function-name">f</span>(<span class="org-variable-name">a</span>, <span class="org-variable-name">b</span>, <span class="org-variable-name">c</span>) {
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">i</span>, <span class="org-variable-name">boo</span>, <span class="org-variable-name">w</span> = 10, <span class="org-variable-name">q</span> = 20;
|
|
<span class="org-keyword">for</span> (i = 1; i < 10; ++i) {
|
|
boo = foo(a);
|
|
}
|
|
<span class="org-keyword">for</span> (i = 0; i < 1; ++i) {
|
|
boo = bar(c);
|
|
}
|
|
<span class="org-keyword">function</span> <span class="org-function-name">foo</span>() { ... }
|
|
<span class="org-keyword">function</span> <span class="org-function-name">bar</span>() { ... }
|
|
}
|
|
</pre>
|
|
|
|
|
|
<ul>
|
|
<li><code>pro.ast_mangle(ast, options)</code> – generates a new AST containing mangled
|
|
(compressed) variable and function names. It supports the following
|
|
options:
|
|
|
|
<ul>
|
|
<li><code>toplevel</code> – mangle toplevel names (by default we don't touch them).
|
|
</li>
|
|
<li><code>except</code> – an array of names to exclude from compression.
|
|
</li>
|
|
<li><code>defines</code> – an object with properties named after symbols to
|
|
replace (see the <code>--define</code> option for the script) and the values
|
|
representing the AST replacement value.
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
<li><code>pro.ast_squeeze(ast, options)</code> – employs further optimizations designed
|
|
to reduce the size of the code that <code>gen_code</code> would generate from the
|
|
AST. Returns a new AST. <code>options</code> can be a hash; the supported options
|
|
are:
|
|
|
|
<ul>
|
|
<li><code>make_seqs</code> (default true) which will cause consecutive statements in a
|
|
block to be merged using the "sequence" (comma) operator
|
|
|
|
</li>
|
|
<li><code>dead_code</code> (default true) which will remove unreachable code.
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
<li><code>pro.gen_code(ast, options)</code> – generates JS code from the AST. By
|
|
default it's minified, but using the <code>options</code> argument you can get nicely
|
|
formatted output. <code>options</code> is, well, optional :-) and if you pass it it
|
|
must be an object and supports the following properties (below you can see
|
|
the default values):
|
|
|
|
<ul>
|
|
<li><code>beautify: false</code> – pass <code>true</code> if you want indented output
|
|
</li>
|
|
<li><code>indent_start: 0</code> (only applies when <code>beautify</code> is <code>true</code>) – initial
|
|
indentation in spaces
|
|
</li>
|
|
<li><code>indent_level: 4</code> (only applies when <code>beautify</code> is <code>true</code>) --
|
|
indentation level, in spaces (pass an even number)
|
|
</li>
|
|
<li><code>quote_keys: false</code> – if you pass <code>true</code> it will quote all keys in
|
|
literal objects
|
|
</li>
|
|
<li><code>space_colon: false</code> (only applies when <code>beautify</code> is <code>true</code>) – wether
|
|
to put a space before the colon in object literals
|
|
</li>
|
|
<li><code>ascii_only: false</code> – pass <code>true</code> if you want to encode non-ASCII
|
|
characters as <code>\uXXXX</code>.
|
|
</li>
|
|
<li><code>inline_script: false</code> – pass <code>true</code> to escape occurrences of
|
|
<code></script</code> in strings
|
|
</li>
|
|
</ul>
|
|
|
|
</li>
|
|
</ul>
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-4-2" class="outline-4">
|
|
<h4 id="sec-1-4-2"><span class="section-number-4">1.4.2</span> Beautifier shortcoming – no more comments </h4>
|
|
<div class="outline-text-4" id="text-1-4-2">
|
|
|
|
|
|
<p>
|
|
The beautifier can be used as a general purpose indentation tool. It's
|
|
useful when you want to make a minified file readable. One limitation,
|
|
though, is that it discards all comments, so you don't really want to use it
|
|
to reformat your code, unless you don't have, or don't care about, comments.
|
|
</p>
|
|
<p>
|
|
In fact it's not the beautifier who discards comments — they are dumped at
|
|
the parsing stage, when we build the initial AST. Comments don't really
|
|
make sense in the AST, and while we could add nodes for them, it would be
|
|
inconvenient because we'd have to add special rules to ignore them at all
|
|
the processing stages.
|
|
</p>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-4-3" class="outline-4">
|
|
<h4 id="sec-1-4-3"><span class="section-number-4">1.4.3</span> Use as a code pre-processor </h4>
|
|
<div class="outline-text-4" id="text-1-4-3">
|
|
|
|
|
|
<p>
|
|
The <code>--define</code> option can be used, particularly when combined with the
|
|
constant folding logic, as a form of pre-processor to enable or remove
|
|
particular constructions, such as might be used for instrumenting
|
|
development code, or to produce variations aimed at a specific
|
|
platform.
|
|
</p>
|
|
<p>
|
|
The code below illustrates the way this can be done, and how the
|
|
symbol replacement is performed.
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="src src-js">CLAUSE1: <span class="org-keyword">if</span> (<span class="org-keyword">typeof</span> DEVMODE === <span class="org-string">'undefined'</span>) {
|
|
DEVMODE = <span class="org-constant">true</span>;
|
|
}
|
|
|
|
<span class="org-function-name">CLAUSE2</span>: <span class="org-keyword">function</span> init() {
|
|
<span class="org-keyword">if</span> (DEVMODE) {
|
|
console.log(<span class="org-string">"init() called"</span>);
|
|
}
|
|
....
|
|
DEVMODE &amp;&amp; console.log(<span class="org-string">"init() complete"</span>);
|
|
}
|
|
|
|
<span class="org-function-name">CLAUSE3</span>: <span class="org-keyword">function</span> reportDeviceStatus(<span class="org-variable-name">device</span>) {
|
|
<span class="org-keyword">var</span> <span class="org-variable-name">DEVMODE</span> = device.mode, <span class="org-variable-name">DEVNAME</span> = device.name;
|
|
<span class="org-keyword">if</span> (DEVMODE === <span class="org-string">'open'</span>) {
|
|
....
|
|
}
|
|
}
|
|
</pre>
|
|
|
|
|
|
<p>
|
|
When the above code is normally executed, the undeclared global
|
|
variable <code>DEVMODE</code> will be assigned the value <b>true</b> (see <code>CLAUSE1</code>)
|
|
and so the <code>init()</code> function (<code>CLAUSE2</code>) will write messages to the
|
|
console log when executed, but in <code>CLAUSE3</code> a locally declared
|
|
variable will mask access to the <code>DEVMODE</code> global symbol.
|
|
</p>
|
|
<p>
|
|
If the above code is processed by UglifyJS with an argument of
|
|
<code>--define DEVMODE=false</code> then UglifyJS will replace <code>DEVMODE</code> with the
|
|
boolean constant value <b>false</b> within <code>CLAUSE1</code> and <code>CLAUSE2</code>, but it
|
|
will leave <code>CLAUSE3</code> as it stands because there <code>DEVMODE</code> resolves to
|
|
a validly declared variable.
|
|
</p>
|
|
<p>
|
|
And more so, the constant-folding features of UglifyJS will recognise
|
|
that the <code>if</code> condition of <code>CLAUSE1</code> is thus always false, and so will
|
|
remove the test and body of <code>CLAUSE1</code> altogether (including the
|
|
otherwise slightly problematical statement <code>false = true;</code> which it
|
|
will have formed by replacing <code>DEVMODE</code> in the body). Similarly,
|
|
within <code>CLAUSE2</code> both calls to <code>console.log()</code> will be removed
|
|
altogether.
|
|
</p>
|
|
<p>
|
|
In this way you can mimic, to a limited degree, the functionality of
|
|
the C/C++ pre-processor to enable or completely remove blocks
|
|
depending on how certain symbols are defined - perhaps using UglifyJS
|
|
to generate different versions of source aimed at different
|
|
environments
|
|
</p>
|
|
<p>
|
|
It is recommmended (but not made mandatory) that symbols designed for
|
|
this purpose are given names consisting of <code>UPPER_CASE_LETTERS</code> to
|
|
distinguish them from other (normal) symbols and avoid the sort of
|
|
clash that <code>CLAUSE3</code> above illustrates.
|
|
</p>
|
|
</div>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-5" class="outline-3">
|
|
<h3 id="sec-1-5"><span class="section-number-3">1.5</span> Compression – how good is it? </h3>
|
|
<div class="outline-text-3" id="text-1-5">
|
|
|
|
|
|
<p>
|
|
Here are updated statistics. (I also updated my Google Closure and YUI
|
|
installations).
|
|
</p>
|
|
<p>
|
|
We're still a lot better than YUI in terms of compression, though slightly
|
|
slower. We're still a lot faster than Closure, and compression after gzip
|
|
is comparable.
|
|
</p>
|
|
<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
|
|
<caption></caption>
|
|
<colgroup><col class="left" /><col class="left" /><col class="right" /><col class="left" /><col class="right" /><col class="left" /><col class="right" />
|
|
</colgroup>
|
|
<thead>
|
|
<tr><th scope="col" class="left">File</th><th scope="col" class="left">UglifyJS</th><th scope="col" class="right">UglifyJS+gzip</th><th scope="col" class="left">Closure</th><th scope="col" class="right">Closure+gzip</th><th scope="col" class="left">YUI</th><th scope="col" class="right">YUI+gzip</th></tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr><td class="left">jquery-1.6.2.js</td><td class="left">91001 (0:01.59)</td><td class="right">31896</td><td class="left">90678 (0:07.40)</td><td class="right">31979</td><td class="left">101527 (0:01.82)</td><td class="right">34646</td></tr>
|
|
<tr><td class="left">paper.js</td><td class="left">142023 (0:01.65)</td><td class="right">43334</td><td class="left">134301 (0:07.42)</td><td class="right">42495</td><td class="left">173383 (0:01.58)</td><td class="right">48785</td></tr>
|
|
<tr><td class="left">prototype.js</td><td class="left">88544 (0:01.09)</td><td class="right">26680</td><td class="left">86955 (0:06.97)</td><td class="right">26326</td><td class="left">92130 (0:00.79)</td><td class="right">28624</td></tr>
|
|
<tr><td class="left">thelib-full.js (DynarchLIB)</td><td class="left">251939 (0:02.55)</td><td class="right">72535</td><td class="left">249911 (0:09.05)</td><td class="right">72696</td><td class="left">258869 (0:01.94)</td><td class="right">76584</td></tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-6" class="outline-3">
|
|
<h3 id="sec-1-6"><span class="section-number-3">1.6</span> Bugs? </h3>
|
|
<div class="outline-text-3" id="text-1-6">
|
|
|
|
|
|
<p>
|
|
Unfortunately, for the time being there is no automated test suite. But I
|
|
ran the compressor manually on non-trivial code, and then I tested that the
|
|
generated code works as expected. A few hundred times.
|
|
</p>
|
|
<p>
|
|
DynarchLIB was started in times when there was no good JS minifier.
|
|
Therefore I was quite religious about trying to write short code manually,
|
|
and as such DL contains a lot of syntactic hacks<sup><a class="footref" name="fnr.1" href="#fn.1">1</a></sup> such as “foo == bar ? a
|
|
= 10 : b = 20”, though the more readable version would clearly be to use
|
|
“if/else”.
|
|
</p>
|
|
<p>
|
|
Since the parser/compressor runs fine on DL and jQuery, I'm quite confident
|
|
that it's solid enough for production use. If you can identify any bugs,
|
|
I'd love to hear about them (<a href="http://groups.google.com/group/uglifyjs">use the Google Group</a> or email me directly).
|
|
</p>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-7" class="outline-3">
|
|
<h3 id="sec-1-7"><span class="section-number-3">1.7</span> Links </h3>
|
|
<div class="outline-text-3" id="text-1-7">
|
|
|
|
|
|
<ul>
|
|
<li>Twitter: <a href="http://twitter.com/UglifyJS">@UglifyJS</a>
|
|
</li>
|
|
<li>Project at GitHub: <a href="http://github.com/mishoo/UglifyJS">http://github.com/mishoo/UglifyJS</a>
|
|
</li>
|
|
<li>Google Group: <a href="http://groups.google.com/group/uglifyjs">http://groups.google.com/group/uglifyjs</a>
|
|
</li>
|
|
<li>Common Lisp JS parser: <a href="http://marijn.haverbeke.nl/parse-js/">http://marijn.haverbeke.nl/parse-js/</a>
|
|
</li>
|
|
<li>JS-to-Lisp compiler: <a href="http://github.com/marijnh/js">http://github.com/marijnh/js</a>
|
|
</li>
|
|
<li>Common Lisp JS uglifier: <a href="http://github.com/mishoo/cl-uglify-js">http://github.com/mishoo/cl-uglify-js</a>
|
|
</li>
|
|
</ul>
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div id="outline-container-1-8" class="outline-3">
|
|
<h3 id="sec-1-8"><span class="section-number-3">1.8</span> License </h3>
|
|
<div class="outline-text-3" id="text-1-8">
|
|
|
|
|
|
<p>
|
|
UglifyJS is released under the BSD license:
|
|
</p>
|
|
|
|
|
|
|
|
<pre class="example">Copyright 2010 (c) Mihai Bazon <mihai.bazon@gmail.com>
|
|
Based on parse-js (http://marijn.haverbeke.nl/parse-js/).
|
|
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions
|
|
are met:
|
|
|
|
* Redistributions of source code must retain the above
|
|
copyright notice, this list of conditions and the following
|
|
disclaimer.
|
|
|
|
* Redistributions in binary form must reproduce the above
|
|
copyright notice, this list of conditions and the following
|
|
disclaimer in the documentation and/or other materials
|
|
provided with the distribution.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
|
|
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
|
|
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
|
|
TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
|
|
THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
SUCH DAMAGE.
|
|
</pre>
|
|
|
|
|
|
<div id="footnotes">
|
|
<h2 class="footnotes">Footnotes: </h2>
|
|
<div id="text-footnotes">
|
|
<p class="footnote"><sup><a class="footnum" name="fn.1" href="#fnr.1">1</a></sup> I even reported a few bugs and suggested some fixes in the original
|
|
<a href="http://marijn.haverbeke.nl/parse-js/">parse-js</a> library, and Marijn pushed fixes literally in minutes.
|
|
</p></div>
|
|
</div>
|
|
</div>
|
|
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
<div id="postamble">
|
|
<p class="date">Date: 2011-12-09 14:59:08 EET</p>
|
|
<p class="author">Author: Mihai Bazon</p>
|
|
<p class="creator">Org version 7.7 with Emacs version 23</p>
|
|
<a href="http://validator.w3.org/check?uri=referer">Validate XHTML 1.0</a>
|
|
|
|
</div>
|
|
</body>
|
|
</html>
|