Package for managing and documenting closure-compiler for use via npm
lauraharker Merge pull request #102 from google/curl-fail
Fail the build script if curl receives a non-success HTTP status code
Latest commit 7ff540d Aug 13, 2018


Build Status npm version

Check, compile, optimize and compress Javascript with Closure-Compiler

This repository tracks issues related to the publication to and associated plugins. Any bugs not related to the plugins themselves should be reported to the main repository.

Getting Started

If you are new to Closure-Compiler, make sure to read and understand the compilation levels as the compiler works very differently depending on the compilation level selected.

For help or questions with the compiler, the best resource is Stack Overflow. Posts there are monitored by multiple Closure Compiler team members.

You may also post in the Closure Compiler Discuss Google Group.

Please don't cross post to both Stackoverflow and Closure Compiler Discuss.

The compiler is distributed as a Java jar and a JavaScript library. Mac OS and Linux also have native binaries.

Native Binary Version

On Mac OS or Linux, optional dependencies will install a native binary of the compiler. Native binaries offer faster compile times without requiring Java to be installed and available. Compilations with a very large number of source files may be slightly slower than the java version.

Java Version

Requires java to be installed and in the path. Using the java version typically results in faster compilation times.

JavaScript Version

This is a transpiled version of the Java source to native JavaScript. It can be used in environments without java installed and even in a browser.

Note: not all flags are available for the JavaScript version.


The simplest way to invoke the compiler (e.g. if you're just trying it out) is with npx:

npx google-closure-compiler --js=my_program.js --js_output_file=out.js

The npx version will attempt to detect the best platform to use. You can also specify the platform with the special --platform flag.


npm install --save google-closure-compiler


See the full list of compiler flags.

The build tool plugins take options objects. The option parameters map directly to the compiler flags without the leading '--' characters. You may also use camelCase option names.

Values are either strings or booleans. Options which have multiple values can be arrays.

    js: ['/file-one.js', '/file-two.js'],
    compilation_level: 'ADVANCED',
    js_output_file: 'out.js',
    debug: true

For the java version, some shells (particularly windows) try to do expansion on globs rather than passing the string on to the compiler. To prevent this it is necessary to quote certain arguments:

    js: '"my/quoted/glob/**.js"',
    compilation_level: 'ADVANCED',
    js_output_file: 'out.js',
    debug: true

Build Tool Plugins

The compiler package also includes build tool plugins for Grunt and Gulp. There is also an official webpack plugin.

Community Maintained Plugins

Additionally, community members have created plugins leveraging this library.

Advanced Java Version Usage

Changing the Path to the Java SDK

Override the path before first use.

const Compiler = require('google-closure-compiler');

Compiler.prototype.javaPath = '/node_modules/MODULE_NAME/jre/jre1.8.0_131.jre/Contents/Home/bin/java';

const compiler = new Compiler({args});

Running the compiler using nailgun

Note: nailgun users are encouraged to try the native binary versions where available.

This gets around the long startup time of Google Closure Compiler using Nailgun, which runs a single java process in the background and keeps all of the classes loaded.

First you need to install closure-gun by running the following command.

npm install closure-gun

Then point the package to use closure-gun rather than the JDK.

const compilerPackage = require('google-closure-compiler');

compilerPackage.compiler.JAR_PATH = undefined;
compilerPackage.compiler.prototype.javaPath = './node_modules/.bin/closure-gun'

Note that when using gulp, Only invocations without gulp.src work with nailgun.

Native Node Usage (for Plugin Authors)

A low-level node class is included to facilitate spawning the compiler jar as a process from Node. In addition, it exposes a static property with the path to the compiler jar file.

Java Version

const ClosureCompiler = require('google-closure-compiler').compiler;

console.log(ClosureCompiler.COMPILER_PATH); // absolute path the compiler jar
console.log(ClosureCompiler.CONTRIB_PATH); // absolute path the contrib folder which contains

const closureCompiler = new ClosureCompiler({
  js: 'file-one.js',
  compilation_level: 'ADVANCED'

const compilerProcess =, stdOut, stdErr) => {
  //compilation complete

JavaScript Version

const ClosureCompiler = require('google-closure-compiler').jsCompiler;

console.log(ClosureCompiler.CONTRIB_PATH); // absolute path the contrib folder which contains

const closureCompiler = new ClosureCompiler({
  compilation_level: 'ADVANCED'

const compilerProcess =[{
 path: 'file-one.js',
 src: 'alert("hello world")',
 sourceMap: null // optional input source map
}], (exitCode, stdOut, stdErr) => {
  //compilation complete


Copyright 2015 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

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.

Version History

Closure Compiler release notes can be found on the main repository wiki.