The 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.
- Download the latest version (Release details here)
- Download a specific version
- See the Google Developers Site for documentation including instructions for running the compiler from the command line.
- Post in the Closure Compiler Discuss Group
- Ask a question on Stack Overflow
- Consult the FAQ
Note: The Closure Compiler requires Java 7 or higher.
Using Ant
-
Download the Ant build tool.
-
At the root of the source tree, there is an Ant file named
build.xml. To use it, navigate to the same directory and type the commandant jarThis will produce a jar file called
build/compiler.jar.
Using Eclipse
- Download and open the Eclipse IDE.
- Navigate to
File > New > Project ...and create a Java Project. Give the project a name. - Select
Create project from existing sourceand choose the root of the checked-out source tree as the existing directory. - Navigate to the
build.xmlfile. You will see all the build rules in the Outline pane. Run thejarrule to build the compiler inbuild/compiler.jar.
On the command line, at the root of this project, type
java -jar build/compiler.jar
This starts the compiler in interactive mode. Type
var x = 17 + 25;then hit "Enter", then hit "Ctrl-Z" (on Windows) or "Ctrl-D" (on Mac or Linux) and "Enter" again. The Compiler will respond:
var x=42;The Closure Compiler has many options for reading input from a file, writing output to a file, checking your code, and running optimizations. To learn more, type
java -jar compiler.jar --help
More detailed information about running the Closure Compiler is available in the documentation.
If you have multiple scripts, you should compile them all together with one compile command.
java -jar compiler.jar --js_output_file=out.js in1.js in2.js in3.js ...You can also use minimatch-style globs.
# Recursively include all js files in subdirs
java -jar compiler.jar --js_output_file=out.js 'src/**.js'
# Recursively include all js files in subdirs, exclusing test files.
# Use single-quotes, so that bash doesn't try to expand the '!'
java -jar compiler.jar --js_output_file=out.js 'src/**.js' '!**_test.js'The Closure Compiler will concatenate the files in the order they're passed at the command line.
If you're using globs or many files, you may start to run into problems with managing dependencies between scripts. In this case, you should use the Closure Library. It contains functions for enforcing dependencies between scripts, and Closure Compiler will re-order the inputs automatically.
- First make sure that it is really a bug and not simply the way that Closure Compiler works (especially true for ADVANCED_OPTIMIZATIONS).
- Check the official documentation
- Consult the FAQ
- Search on Stack Overflow and in the Closure Compiler Discuss Group
- If you still think you have found a bug, make sure someone hasn't already reported it. See the list of known issues.
- 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.
- Consult the FAQ to make sure that the behaviour you would like isn't specifically excluded (such as string inlining).
- Make sure someone hasn't requested the same thing. See the list of known issues.
- Read up on what type of feature requests are accepted.
- Submit your reqest as an issue.
- All contributors must sign a contributor license agreement. See the CONTRIBUTORS file for details.
- To make sure your changes are of the type that will be accepted, ask about your patch on the Closure Compiler Discuss Group
- Fork the repository.
- Make your changes.
- Submit a pull request for your changes. A project developer will review your work and then merge your request into the project.
Copyright 2009 The Closure Compiler Authors.
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.
| Code Path |
src/com/google/javascript/rhino, test/com/google/javascript/rhino
|
| URL | http://www.mozilla.org/rhino |
| Version | 1.5R3, with heavy modifications |
| License | Netscape Public License and MPL / GPL dual license |
| Description | A partial copy of Mozilla Rhino. Mozilla Rhino is an implementation of JavaScript for the JVM. The JavaScript parse tree data structures were extracted and modified significantly for use by Google's JavaScript compiler. |
| Local Modifications | The packages have been renamespaced. All code not relevant to the parse tree has been removed. A JsDoc parser and static typing system have been added. |
| Code Path | lib/args4j.jar |
| URL | https://args4j.dev.java.net/ |
| Version | 2.0.26 |
| License | MIT |
| Description | args4j is a small Java class library that makes it easy to parse command line options/arguments in your CUI application. |
| Local Modifications | None |
| Code Path | lib/guava.jar |
| URL | https://github.com/google/guava |
| Version | 18.0 |
| License | Apache License 2.0 |
| Description | Google's core Java libraries. |
| Local Modifications | None |
| Code Path | lib/jsr305.jar |
| URL | http://code.google.com/p/jsr-305/ |
| Version | svn revision 47 |
| License | BSD License |
| Description | Annotations for software defect detection. |
| Local Modifications | None |
| Code Path | lib/junit.jar |
| URL | http://sourceforge.net/projects/junit/ |
| Version | 4.11 |
| License | Common Public License 1.0 |
| Description | A framework for writing and running automated tests in Java. |
| Local Modifications | None |
| Code Path | lib/protobuf-java.jar |
| URL | http://code.google.com/p/protobuf/ |
| Version | 2.5.0 |
| License | New BSD License |
| Description | Supporting libraries for protocol buffers, an encoding of structured data. |
| Local Modifications | None |
| Code Path |
lib/ant.jar, lib/ant-launcher.jar
|
| URL | http://ant.apache.org/bindownload.cgi |
| Version | 1.8.1 |
| License | Apache License 2.0 |
| Description | Ant is a Java based build tool. In theory it is kind of like "make" without make's wrinkles and with the full portability of pure java code. |
| Local Modifications | None |
| Code Path | lib/gson.jar |
| URL | https://code.google.com/p/google-gson/ |
| Version | 2.2.4 |
| License | Apache license 2.0 |
| Description | A Java library to convert JSON to Java objects and vice-versa |
| Local Modifications | None |
| Code Path | lib/mockito-core.jar |
| URL | https://code.google.com/p/mockito |
| Version | 1.9.5 |
| License | MIT license |
| Description | Mockito is an open source testing framework for Java. The framework allows the creation of Test Double objects (called "Mock Objects") in automated unit tests for the purpose of Test-driven Development (TDD) or Behavior Driven Development (BDD). |
| Local Modifications | None |
| Code Path | lib/objenesis.jar |
| URL | http://objenesis.org |
| Version | 1.2 |
| License | Apache 2.0 license |
| Description | Depended by lib/mockito-core.jar, not used directly. |
| Local Modifications | None |
| Code Path | contrib/nodejs |
| URL | https://github.com/dcodeIO/node.js-closure-compiler-externs |
| Version | e891b4fbcf5f466cc4307b0fa842a7d8163a073a |
| License | Apache 2.0 license |
| Description | Type contracts for NodeJS APIs |
| Local Modifications | Substantial changes to make them compatible with NpmCommandLineRunner. |