@wordpress/dependency-extraction-webpack-plugin Edit

This webpack plugin serves two purposes:

  • Externalize dependencies that are available as script dependencies on modern WordPress sites.
  • Add a JSON file for each entrypoint that declares the WordPress script dependencies for the
    entrypoint.

This allows JavaScript bundles produced by webpack to leverage WordPress style dependency sharing
without an error-prone process of manually maintaining a dependency list.

Consult the webpack website for additional information on webpack concepts.

Installation Installation

Install the module

npm install @wordpress/dependency-extraction-webpack-plugin --save-dev

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Usage Usage

Webpack Webpack

Use this plugin as you would other webpack plugins:

// webpack.config.js
const DependencyExtractionWebpackPlugin = require( '@wordpress/dependency-extraction-webpack-plugin' );

module.exports = {
  // …snip
  plugins: [
    new DependencyExtractionWebpackPlugin(),
  ]
}

Note: Multiple instances of the plugin are not supported and may produced unexpected results. If
you plan to extend the webpack configuration from @wordpress/scripts with your own DependencyExtractionWebpackPlugin, be sure to
remove the default instance of the plugin:

const defaultConfig = require( '@wordpress/scripts/config/webpack.config' );
const config = {
  ...defaultConfig,
  plugins: [
    ...defaultConfig.plugins.filter(
      plugin => plugin.constructor.name !== 'DependencyExtractionWebpackPlugin',
    ),
    new DependencyExtractionWebpackPlugin( {
      injectPolyfill: true,
      requestToExternal(request) {
        /* My externals */
      },
    } ),
  ],
};

Each entrypoint in the webpack bundle will include JSON file that declares the WordPress script dependencies that should be enqueued.

For example:

// Source file entrypoint.js
import { Component } from '@wordpress/element';

// Webpack will produce the output output/entrypoint.js
/* bundled JavaScript output */

// Webpack will also produce output/entrypoint.deps.json declaring script dependencies
['wp-element']

By default, the following module requests are handled:

Request Global Script handle
@babel/runtime/regenerator regeneratorRuntime wp-polyfill
@wordpress/* wp['*'] wp-*
jquery jQuery jquery
lodash-es lodash lodash
lodash lodash lodash
moment moment moment
react-dom ReactDOM react-dom
react React react

Note: This plugin overlaps with the functionality provided by webpack
externals
. This plugin is intended to extract
script handles from bundle compilation so that a list of script dependencies does not need to be
manually maintained. If you don’t need to extract a list of script dependencies, use the externals
option directly.

This plugin is compatible with externals, but they may conflict. For example, adding
{ externals: { '@wordpress/blob': 'wp.blob' } } to webpack configuration will effectively hide the
@wordpress/blob module from the plugin and it will not be included in dependency lists.

Options Options

An object can be passed to the constructor to customize the behavior, for example:

module.exports = {
  plugins: [
    new DependencyExtractionWebpackPlugin( { injectPolyfill: true } ),
  ]
}
useDefaults
  • Type: boolean
  • Default: true

Pass useDefaults: false to disable the default request handling.

injectPolyfill
  • Type: boolean
  • Default: false

Force wp-polyfill to be included in each entrypoint’s dependency list. This would be the same as
adding import '@wordpress/polyfill'; to each entrypoint.

requestToExternal
  • Type: function

requestToExternal allows the module handling to be customized. The function should accept a
module request string and may return a string representing the global variable to use. An array of
strings may be used to access globals via an object path, e.g. wp.i18n may be represented as [
'wp', 'i18n' ]
.

requestToExternal provided via configuration has precedence over default external handling.
Unhandled requests will be handled by the default unless useDefaults is set to false.

/**
 * Externalize 'my-module'
 *
 * @param {string} request Requested module
 *
 * @return {(string|undefined)} Script global
 */
function requestToExternal( request ) {

  // Handle imports like `import myModule from 'my-module'`
  if ( request === 'my-module' ) {
    // Expect to find `my-module` as myModule in the global scope:
    return 'myModule';
  }
}

module.exports = {
  plugins: [
    new DependencyExtractionWebpackPlugin( { requestToExternal } ),
  ]
}
requestToHandle
  • Type: function

All of the external modules handled by the plugin are expected to be WordPress script dependencies
and will be added to the dependency list. requestToHandle allows the script handle included in the dependency list to be customized.

If no string is returned, the script handle is assumed to be the same as the request.

requestToHandle provided via configuration has precedence over the defaults. Unhandled requests will be handled by the default unless useDefaults is set to false.

/**
 * Map 'my-module' request to 'my-module-script-handle'
 *
 * @param {string} request Requested module
 *
 * @return {(string|undefined)} Script global
 */
function requestToHandle( request ) {

  // Handle imports like `import myModule from 'my-module'`
  if ( request === 'my-module' ) {
    // `my-module` depends on the script with the 'my-module-script-handle' handle.
    return 'my-module-script-handle';
  }
}

module.exports = {
  plugins: [
    new DependencyExtractionWebpackPlugin( { requestToExternal } ),
  ]
}
requestToExternal and requestToHandle

The functions requestToExternal and requestToHandle allow this module to handle arbitrary
modules. requestToExternal is necessary to handle any module and maps a module request to a global
name. requestToHandle maps the same module request to a script handle, the strings that will be
included in the entrypoint.deps.json files.

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WordPress WordPress

Enqueue your script as usual and read the script dependencies dynamically:

$script_path         = 'path/to/script.js';
$script_deps_path    = 'path/to/script.deps.json';
$script_dependencies = file_exists( $script_deps_path )
    ? json_decode( file_get_contents( $script_deps_path ) )
    : array();
$script_url = plugins_url( $script_path, __FILE__ );
wp_enqueue_script( 'script', $script_url, $script_dependencies );

Code is Poetry.