closure-compiler-js

Check, compile, transpile, optimize and compress JavaScript with Closure Compiler in JS

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

Unlike other packages, this allows Closure Compiler to run entirely in JS. Java is not required.

This is an experimental release- some features are not available and performance may not be on-par with the Java implementation.

Usage

First, install the latest version-

npm install --save google-closure-compiler-js

The module supports modern web browsers as well as Node v4 LTS, and provides compile as a low-level method to compile JavaScript. By default, this compiles ES6 to ES5 and includes the default set of ECMAScript externs files. For example-

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

const flags = {
  jsCode: [{src: 'const x = 1 + 2;'}],
};
const out = compile(flags);
console.info(out.compiledCode);  // will print 'var x = 3;\n'

Build Systems

Webpack

Your webpack.config.js should look like this-

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

module.exports = {
  entry: [
    path.join(__dirname, 'app.js')
  ],
  output: {
    path: path.join(__dirname, 'dist'),
    filename: 'app.min.js'
  },
  plugins: [
    new ClosureCompiler({
      options: {
        languageIn: 'ECMASCRIPT6',
        languageOut: 'ECMASCRIPT5',
        compilationLevel: 'ADVANCED',
        warningLevel: 'VERBOSE',
      },
    })
  ]
};

Gulp

Your gulpfile.js should contain a task like this-

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

gulp.task('script', function() {
  return gulp.src('./path/to/src.js', {base: './'})
      // your other steps here
      .pipe(compiler({
          compilationLevel: 'SIMPLE',
          warningLevel: 'VERBOSE',
          jsOutputFile: 'output.min.js',  // outputs single file
          createSourceMap: true,
        }))
      .pipe(gulp.dest('./dist'));
});

Flags

Flag	Default	Usage
angularPass	false	Generate $inject properties for AngularJS for functions annotated with @ngInject
assumeFunctionWrapper	false	Enable additional optimizations based on the assumption that the output will be wrapped with a function wrapper. This flag is used to indicate that "global" declarations will not actually be global but instead isolated to the compilation unit. This enables additional optimizations.
checksOnly	false	Don't generate output. Run checks, but no optimization passes.
compilationLevel	SIMPLE	Specifies the compilation level to use. Options: WHITESPACE_ONLY, SIMPLE, ADVANCED
dartPass	false
env	BROWSER	Determines the set of builtin externs to load. Options: BROWSER, CUSTOM
exportLocalPropertyDefinitions	false
generateExports	false	Generates export code for those marked with @export.
languageIn	ES6	Sets what language spec that input sources conform to.
languageOut	ES5	Sets what language spec the output should conform to.
newTypeInf	false	Checks for type errors using the new type inference algorithm.
polymerPass	false	Rewrite Polymer classes to be compiler-friendly.
preserveTypeAnnotations	false
processCommonJsModules	false	Process CommonJS modules to a concatenable form, i.e., support require statements.
renamePrefixNamespace		Specifies the name of an object that will be used to store all non-extern globals.
rewritePolyfills	false	Rewrite ES6 library calls to use polyfills provided by the compiler's runtime.
useTypesForOptimization	false	Enable or disable the optimizations based on available type information. Inaccurate type annotations may result in incorrect results.
warningLevel	DEFAULT	Specifies the warning level to use. Options: QUIET, DEFAULT, VERBOSE
jsCode	[]	Specifies the source code to compile.
externs	[]	Additional externs to use for this compile.
createSourceMap	false	Generates a source map mapping the generated source file back to its original sources.

Languages

The Closure Compiler supports languages ECMASCRIPT3, ECMASCRIPT5, ECMASCRIPT5_STRICT for input and output, ECMASCRIPT6, ECMASCRIPT6_STRICT for input only, and ECMASCRIPT6_TYPED (experimental) for both.

Source Code

Unless you're using the Gulp or Webpack plugins, you'll need to specify code via flags. Both jsCode and externs accept an array containing objects in the form {src, path, sourceMap}. Using path, you can construct a virtual filesystem for use with ES6 or CommonJS imports—although for CommonJS, be sure to set processCommonJsModules: true.

License

Copyright 2016 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.

Version History

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