Developer Documentation

Webpack Asset Loader

This feature makes it easy to detect and load assets generated by Webpack, including those served from local webpack-dev-server instances.

Usage

The Asset Loader library is designed to work in conjunction with a Webpack configuration (such as those created with the presets in @humanmade/webpack-helpers) which generate an asset manifest file. This manifest associates asset bundle names with either URIs pointing to asset bundles on a running DevServer instance, or else local file paths on disk.

Asset_Loader\register_asset() and Asset_Loader\enqueue_asset()

Asset_Loader provides a set of methods for reading this manifest file and registering a specific resource within it to load within your WordPress website. The primary public interface provided by this plugin is a pair of methods, Asset_Loader\register_asset() and Asset_Loader\enqueue_asset(). To register a manifest asset call one of these methods inside actions like wp_enqueue_scripts or enqueue_block_editor_assets, in the same manner you would have called the standard WordPress wp_register_script or wp_enqueue_style functions.

Both functions accept the following parameters:

  • string $manifest_path: The path on disk to the generated manifest file.
  • string $target_asset: The asset output name defined in the Webpack configuration.
  • array $options: An array of options to control how the asset is registered and loaded.
    • bool 'in-footer': Whether to load the asset in the footer or of the page or the <head>. Default to true.
    • array 'dependencies: An array of script or style handles this asset is dependent upon.
    • string 'handle': An optional custom handle to use for referring to the asset. Defaults to the value of $target_asset.

To register an asset to be manually enqueued later, use Asset_Loader\register_asset() instead of Asset_Loader\enqueue_asset().

The following example shows how to enqueue a JS and a CSS file for the Block Editor:

<?php
namespace My_Theme\Scripts;

use Asset_Loader;

add_action( 'enqueue_block_editor_assets', __NAMESPACE__ . '\\enqueue_block_editor_assets' );

/**
 * Enqueue the JS and CSS for blocks in the editor.
 *
 * @return void
 */
function enqueue_block_editor_assets() {
  Asset_Loader\enqueue_asset(
    // In a plugin, this would be `plugin_dir_path( __FILE__ )` or similar.
    get_stylesheet_directory() . '/build/asset-manifest.json',
    // The handle of a resource within the manifest. For static file fallbacks,
    // this should also match the filename on disk of a build production asset.
    'blocks.js',
    [
      'handle' => 'my-theme-blocks',
      'dependencies' => [ 'wp-data', 'wp-element', 'wp-editor' ],
    ]
  );

  Asset_Loader\enqueue_asset(
    // In a plugin, this would be `plugin_dir_path( __FILE__ )` or similar.
    get_stylesheet_directory() . '/build/asset-manifest.json',
    // Enqueue CSS for the editor.
    'blocks.css',
    [
      'handle' => 'my-theme-blocks-style',
      'dependencies' => [ 'wp-components' ],
    ]
  );
}