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1# [Google Closure Compiler](https://developers.google.com/closure/compiler/)
2
3[![Build Status](https://travis-ci.org/google/closure-compiler.svg?branch=master)](https://travis-ci.org/google/closure-compiler)
4
5The [Closure Compiler](https://developers.google.com/closure/compiler/) is a tool for making JavaScript download and run faster. It is a true compiler for JavaScript. Instead of compiling from a source language to machine code, it compiles from JavaScript to better JavaScript. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls.
6
7## Getting Started
8 * [Download the latest version](http://dl.google.com/closure-compiler/compiler-latest.zip) ([Release details here](https://github.com/google/closure-compiler/wiki/Releases))
9 * [Download a specific version](https://github.com/google/closure-compiler/wiki/Binary-Downloads). Also available via:
10   - [Maven](https://github.com/google/closure-compiler/wiki/Maven)
11   - [NPM](https://www.npmjs.com/package/google-closure-compiler)
12 * See the [Google Developers Site](https://developers.google.com/closure/compiler/docs/gettingstarted_app) for documentation including instructions for running the compiler from the command line.
13
14## Options for Getting Help
151. Post in the [Closure Compiler Discuss Group](https://groups.google.com/forum/#!forum/closure-compiler-discuss)
162. Ask a question on [Stack Overflow](http://stackoverflow.com/questions/tagged/google-closure-compiler)
173. Consult the [FAQ](https://github.com/google/closure-compiler/wiki/FAQ)
18
19## Building it Yourself
20
21Note: The Closure Compiler requires [Java 7 or higher](http://www.java.com/).
22
23### Using [Maven](http://maven.apache.org/)
24
251. Download [Maven](http://maven.apache.org/download.cgi).
26
272. Add sonatype snapshots repository to `~/.m2/settings.xml`:
28   ```
29   <profile>
30     <id>allow-snapshots</id>
31        <activation><activeByDefault>true</activeByDefault></activation>
32     <repositories>
33       <repository>
34         <id>snapshots-repo</id>
35         <url>https://oss.sonatype.org/content/repositories/snapshots</url>
36         <releases><enabled>false</enabled></releases>
37         <snapshots><enabled>true</enabled></snapshots>
38       </repository>
39     </repositories>
40   </profile>
41   ```
42
433. Run `mvn -DskipTests` (omit the `-DskipTests` if you want to run all the
44unit tests too).
45
46    This will produce a jar file called `target/closure-compiler-1.0-SNAPSHOT.jar`.
47
48### Using [Eclipse](http://www.eclipse.org/)
49
501. Download and open the [Eclipse IDE](http://www.eclipse.org/).
512. Navigate to `File > New > Project ...` and create a Java Project. Give
52   the project a name.
533. Select `Create project from existing source` and choose the root of the
54   checked-out source tree as the existing directory.
553. Navigate to the `build.xml` file. You will see all the build rules in
56   the Outline pane. Run the `jar` rule to build the compiler in
57   `build/compiler.jar`.
58
59## Running
60
61On the command line, at the root of this project, type
62
63```
64java -jar target/closure-compiler-1.0-SNAPSHOT.jar
65```
66
67This starts the compiler in interactive mode. Type
68
69```javascript
70var x = 17 + 25;
71```
72
73then hit "Enter", then hit "Ctrl-Z" (on Windows) or "Ctrl-D" (on Mac or Linux)
74and "Enter" again. The Compiler will respond:
75
76```javascript
77var x=42;
78```
79
80The Closure Compiler has many options for reading input from a file, writing
81output to a file, checking your code, and running optimizations. To learn more,
82type
83
84```
85java -jar compiler.jar --help
86```
87
88More detailed information about running the Closure Compiler is available in the
89[documentation](http://code.google.com/closure/compiler/docs/gettingstarted_app.html).
90
91## Compiling Multiple Scripts
92
93If you have multiple scripts, you should compile them all together with one
94compile command.
95
96```bash
97java -jar compiler.jar --js_output_file=out.js in1.js in2.js in3.js ...
98```
99
100You can also use minimatch-style globs.
101
102```bash
103# Recursively include all js files in subdirs
104java -jar compiler.jar --js_output_file=out.js 'src/**.js'
105
106# Recursively include all js files in subdirs, excluding test files.
107# Use single-quotes, so that bash doesn't try to expand the '!'
108java -jar compiler.jar --js_output_file=out.js 'src/**.js' '!**_test.js'
109```
110
111The Closure Compiler will concatenate the files in the order they're passed at
112the command line.
113
114If you're using globs or many files, you may start to run into
115problems with managing dependencies between scripts. In this case, you should
116use the [Closure Library](https://developers.google.com/closure/library/). It
117contains functions for enforcing dependencies between scripts, and Closure Compiler
118will re-order the inputs automatically.
119
120## How to Contribute
121### Reporting a bug
1221. First make sure that it is really a bug and not simply the way that Closure Compiler works (especially true for ADVANCED_OPTIMIZATIONS).
123 * Check the [official documentation](https://developers.google.com/closure/compiler/)
124 * Consult the [FAQ](https://github.com/google/closure-compiler/wiki/FAQ)
125 * Search on [Stack Overflow](http://stackoverflow.com/questions/tagged/google-closure-compiler) and in the [Closure Compiler Discuss Group](https://groups.google.com/forum/#!forum/closure-compiler-discuss)
1262. If you still think you have found a bug, make sure someone hasn't already reported it. See the list of [known issues](https://github.com/google/closure-compiler/issues).
1273. If it hasn't been reported yet, post a new issue. Make sure to add enough detail so that the bug can be recreated. The smaller the reproduction code, the better.
128
129### Suggesting a Feature
1301. Consult the [FAQ](https://github.com/google/closure-compiler/wiki/FAQ) to make sure that the behaviour you would like isn't specifically excluded (such as string inlining).
1312. Make sure someone hasn't requested the same thing. See the list of [known issues](https://github.com/google/closure-compiler/issues).
1323. Read up on [what type of feature requests are accepted](https://github.com/google/closure-compiler/wiki/FAQ#how-do-i-submit-a-feature-request-for-a-new-type-of-optimization).
1334. Submit your request as an issue.
134
135### Submitting patches
1361. All contributors must sign a contributor license agreement (CLA).
137   A CLA basically says that you own the rights to any code you contribute,
138   and that you give us permission to use that code in Closure Compiler.
139   You maintain the copyright on that code.
140   If you own all the rights to your code, you can fill out an
141   [individual CLA](http://code.google.com/legal/individual-cla-v1.0.html).
142   If your employer has any rights to your code, then they also need to fill out
143   a [corporate CLA](http://code.google.com/legal/corporate-cla-v1.0.html).
144   If you don't know if your employer has any rights to your code, you should
145   ask before signing anything.
146   By default, anyone with an @google.com email address already has a CLA
147   signed for them.
1482. To make sure your changes are of the type that will be accepted, ask about your patch on the [Closure Compiler Discuss Group](https://groups.google.com/forum/#!forum/closure-compiler-discuss)
1493. Fork the repository.
1504. Make your changes.
1515. Submit a pull request for your changes. A project developer will review your work and then merge your request into the project.
152
153## Closure Compiler License
154
155Copyright 2009 The Closure Compiler Authors.
156
157Licensed under the Apache License, Version 2.0 (the "License");
158you may not use this file except in compliance with the License.
159You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.
160
161Unless required by applicable law or agreed to in writing, software
162distributed under the License is distributed on an "AS IS" BASIS,
163WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
164See the License for the specific language governing permissions and
165limitations under the License.
166
167## Dependency Licenses
168
169### Rhino
170
171<table>
172  <tr>
173    <td>Code Path</td>
174    <td>
175      <code>src/com/google/javascript/rhino</code>, <code>test/com/google/javascript/rhino</code>
176    </td>
177  </tr>
178
179  <tr>
180    <td>URL</td>
181    <td>http://www.mozilla.org/rhino</td>
182  </tr>
183
184  <tr>
185    <td>Version</td>
186    <td>1.5R3, with heavy modifications</td>
187  </tr>
188
189  <tr>
190    <td>License</td>
191    <td>Netscape Public License and MPL / GPL dual license</td>
192  </tr>
193
194  <tr>
195    <td>Description</td>
196    <td>A partial copy of Mozilla Rhino. Mozilla Rhino is an
197implementation of JavaScript for the JVM.  The JavaScript
198parse tree data structures were extracted and modified
199significantly for use by Google's JavaScript compiler.</td>
200  </tr>
201
202  <tr>
203    <td>Local Modifications</td>
204    <td>The packages have been renamespaced. All code not
205relevant to the parse tree has been removed. A JsDoc parser and static typing
206system have been added.</td>
207  </tr>
208</table>
209
210### Args4j
211
212<table>
213  <tr>
214    <td>Code Path</td>
215    <td><code>lib/args4j.jar</code></td>
216  </tr>
217
218  <tr>
219    <td>URL</td>
220    <td>https://args4j.dev.java.net/</td>
221  </tr>
222
223  <tr>
224    <td>Version</td>
225    <td>2.0.26</td>
226  </tr>
227
228  <tr>
229    <td>License</td>
230    <td>MIT</td>
231  </tr>
232
233  <tr>
234    <td>Description</td>
235    <td>args4j is a small Java class library that makes it easy to parse command line
236options/arguments in your CUI application.</td>
237  </tr>
238
239  <tr>
240    <td>Local Modifications</td>
241    <td>None</td>
242  </tr>
243</table>
244
245### Guava Libraries
246
247<table>
248  <tr>
249    <td>Code Path</td>
250    <td><code>lib/guava.jar</code></td>
251  </tr>
252
253  <tr>
254    <td>URL</td>
255    <td>https://github.com/google/guava</td>
256  </tr>
257
258  <tr>
259    <td>Version</td>
260    <td>20.0</td>
261  </tr>
262
263  <tr>
264    <td>License</td>
265    <td>Apache License 2.0</td>
266  </tr>
267
268  <tr>
269    <td>Description</td>
270    <td>Google's core Java libraries.</td>
271  </tr>
272
273  <tr>
274    <td>Local Modifications</td>
275    <td>None</td>
276  </tr>
277</table>
278
279### JSR 305
280
281<table>
282  <tr>
283    <td>Code Path</td>
284    <td><code>lib/jsr305.jar</code></td>
285  </tr>
286
287  <tr>
288    <td>URL</td>
289    <td>http://code.google.com/p/jsr-305/</td>
290  </tr>
291
292  <tr>
293    <td>Version</td>
294    <td>svn revision 47</td>
295  </tr>
296
297  <tr>
298    <td>License</td>
299    <td>BSD License</td>
300  </tr>
301
302  <tr>
303    <td>Description</td>
304    <td>Annotations for software defect detection.</td>
305  </tr>
306
307  <tr>
308    <td>Local Modifications</td>
309    <td>None</td>
310  </tr>
311</table>
312
313### JUnit
314
315<table>
316  <tr>
317    <td>Code Path</td>
318    <td><code>lib/junit.jar</code></td>
319  </tr>
320
321  <tr>
322    <td>URL</td>
323    <td>http://sourceforge.net/projects/junit/</td>
324  </tr>
325
326  <tr>
327    <td>Version</td>
328    <td>4.11</td>
329  </tr>
330
331  <tr>
332    <td>License</td>
333    <td>Common Public License 1.0</td>
334  </tr>
335
336  <tr>
337    <td>Description</td>
338    <td>A framework for writing and running automated tests in Java.</td>
339  </tr>
340
341  <tr>
342    <td>Local Modifications</td>
343    <td>None</td>
344  </tr>
345</table>
346
347### Protocol Buffers
348
349<table>
350  <tr>
351    <td>Code Path</td>
352    <td><code>lib/protobuf-java.jar</code></td>
353  </tr>
354
355  <tr>
356    <td>URL</td>
357    <td>https://github.com/google/protobuf</td>
358  </tr>
359
360  <tr>
361    <td>Version</td>
362    <td>2.5.0</td>
363  </tr>
364
365  <tr>
366    <td>License</td>
367    <td>New BSD License</td>
368  </tr>
369
370  <tr>
371    <td>Description</td>
372    <td>Supporting libraries for protocol buffers,
373an encoding of structured data.</td>
374  </tr>
375
376  <tr>
377    <td>Local Modifications</td>
378    <td>None</td>
379  </tr>
380</table>
381
382### Truth
383
384<table>
385  <tr>
386    <td>Code Path</td>
387    <td><code>lib/truth.jar</code></td>
388  </tr>
389
390  <tr>
391    <td>URL</td>
392    <td>https://github.com/google/truth</td>
393  </tr>
394
395  <tr>
396    <td>Version</td>
397    <td>0.24</td>
398  </tr>
399
400  <tr>
401    <td>License</td>
402    <td>Apache License 2.0</td>
403  </tr>
404
405  <tr>
406    <td>Description</td>
407    <td>Assertion/Proposition framework for Java unit tests</td>
408  </tr>
409
410  <tr>
411    <td>Local Modifications</td>
412    <td>None</td>
413  </tr>
414</table>
415
416### Ant
417
418<table>
419  <tr>
420    <td>Code Path</td>
421    <td>
422      <code>lib/ant.jar</code>, <code>lib/ant-launcher.jar</code>
423    </td>
424  </tr>
425
426  <tr>
427    <td>URL</td>
428    <td>http://ant.apache.org/bindownload.cgi</td>
429  </tr>
430
431  <tr>
432    <td>Version</td>
433    <td>1.8.1</td>
434  </tr>
435
436  <tr>
437    <td>License</td>
438    <td>Apache License 2.0</td>
439  </tr>
440
441  <tr>
442    <td>Description</td>
443    <td>Ant is a Java based build tool. In theory it is kind of like "make"
444without make's wrinkles and with the full portability of pure java code.</td>
445  </tr>
446
447  <tr>
448    <td>Local Modifications</td>
449    <td>None</td>
450  </tr>
451</table>
452
453### GSON
454
455<table>
456  <tr>
457    <td>Code Path</td>
458    <td><code>lib/gson.jar</code></td>
459  </tr>
460
461  <tr>
462    <td>URL</td>
463    <td>https://github.com/google/gson</td>
464  </tr>
465
466  <tr>
467    <td>Version</td>
468    <td>2.2.4</td>
469  </tr>
470
471  <tr>
472    <td>License</td>
473    <td>Apache license 2.0</td>
474  </tr>
475
476  <tr>
477    <td>Description</td>
478    <td>A Java library to convert JSON to Java objects and vice-versa</td>
479  </tr>
480
481  <tr>
482    <td>Local Modifications</td>
483    <td>None</td>
484  </tr>
485</table>
486
487### Node.js Closure Compiler Externs
488
489<table>
490  <tr>
491    <td>Code Path</td>
492    <td><code>contrib/nodejs</code></td>
493  </tr>
494
495  <tr>
496    <td>URL</td>
497    <td>https://github.com/dcodeIO/node.js-closure-compiler-externs</td>
498  </tr>
499
500  <tr>
501    <td>Version</td>
502    <td>e891b4fbcf5f466cc4307b0fa842a7d8163a073a</td>
503  </tr>
504
505  <tr>
506    <td>License</td>
507    <td>Apache 2.0 license</td>
508  </tr>
509
510  <tr>
511    <td>Description</td>
512    <td>Type contracts for NodeJS APIs</td>
513  </tr>
514
515  <tr>
516    <td>Local Modifications</td>
517    <td>Substantial changes to make them compatible with NpmCommandLineRunner.</td>
518  </tr>
519</table>
520