closure-webpack-plugin


This plugin supports the use of Google's Closure Tools with webpack.

Note: This is the webpack 4 branch.

Closure-Compiler is a full optimizing compiler and transpiler.
It offers unmatched optimizations, provides type checking and can easily target transpilation to different versions of ECMASCRIPT.

Closure-Library is a utility library designed for full compatibility
with Closure-Compiler.

Older Versions

For webpack 3 support, see https://github.com/webpack-contrib/closure-webpack-plugin/tree/webpack-3

Install

You must install both the google-closure-compiler package as well as the closure-webpack-plugin.

``
npm install --save-dev closure-webpack-plugin google-closure-compiler
`

Usage example

`js
const ClosurePlugin = require('closure-webpack-plugin');

module.exports = {
optimization: {
minimizer: [
new ClosurePlugin({mode: 'STANDARD'}, {
// compiler flags here
//
// for debugging help, try these:
//
// formatting: 'PRETTY_PRINT'
// debug: true,
// renaming: false
})
]
}
};
`

Options

* platform - native, java or javascript. Controls which version to use of closure-compiler.
By default the plugin will attempt to automatically choose the fastest option available.
- JAVASCRIPT does not require the JVM to be installed. Not all flags are supported.
- JAVA utilizes the jvm. Utilizes multiple threads for parsing and results in faster compilation for large builds.
- NATIVE only available on linux or MacOS. Faster compilation times without requiring a JVM.
* mode - STANDARD (default) or AGGRESSIVE_BUNDLE. Controls how the plugin utilizes the compiler.
- STANDARD mode, closure-compiler is used as a direct replacement for other minifiers as well as most Babel transformations.
- AGGRESSIVE_BUNDLE mode, the compiler performs additional optimizations of modules to produce a much smaller file
* childCompilations - boolean or function. Defaults to false.
In order to decrease build times, this plugin by default only operates on the main compilation.
Plugins such as extract-text-plugin and html-webpack-plugin run as child compilations and
usually do not need transpilation or minification. You can enable this for all child compilations
by setting this option to true. For specific control, the option can be set to a function which
will be passed a compilation object.
Example: function(compilation) { return /html-webpack/.test(compilation.name); }.
* output - An object with either filename or chunkfilename properties. Used to override the
output file naming for a particular compilation. See https://webpack.js.org/configuration/output/
for details.
* test - An optional string or regular expression to determine whether a chunk is included in the compilation
* extraCommandArgs - Optional string or Array of strings to pass to the google-closure-compiler plugin.
Can be used to pass flags to the java process.



Compiler Flags

The plugin controls several compiler flags. The following flags should not be used in any mode:

* module_resolution
* output_wrapper
* dependency_mode
* create_source_map
* module
* entry_point

Aggressive Bundle Mode

In this mode, the compiler rewrites CommonJS modules and hoists require calls. Some modules are not compatible with this type of rewriting. In particular, hoisting will cause the following code to execute out of order:

`js
const foo = require('foo');
addPolyfillToFoo(foo);
const bar = require('bar');
`

Aggressive Bundle Mode utilizes a custom runtime in which modules within a chunk file are all included in the same scope.
This avoids the cost of small modules.

In Aggressive Bundle Mode, a file can only appear in a single output chunk. Use the Split Chunks Plugin
to split duplicated files into a single output chunk. If a module is utilized by more than one chunk, the
plugin will move it up to the first common parent to prevent code duplication.

The concatenatedModules optimization
is not compatible with this mode since Closure-Compiler performs an equivalent optimization).
The plugin will emit a warning if this optimization is not disabled.

Multiple Output Languages

You can add the plugin multiple times. This easily allows you to target multiple output languages.
Use ECMASCRIPT_2015 for modern browsers and ECMASCRIPT5 for older browsers.

Use the output option to change the filenames of specific plugin instances.

Use