WordPress Plugin Build Tools

Model note: Config setup and .asset.php enqueue patterns are mechanical — haiku covers most cases. Debugging webpack entry-point conflicts or reusing a dependency plugin's bundled library may need sonnet.

Configure and operate the JS/CSS build pipeline for WordPress plugins: @wordpress/scripts (webpack-based), Vite alternative, asset manifest handling, and correct enqueuing with the generated .asset.php dependency file.

When to use

• "Set up @wordpress/scripts", "configure webpack for my plugin".
• "Build blocks and admin scripts", "compile Sass for a plugin".
• "Why isn't my JS loading?", "fix asset enqueue with versioned hash".
• "Switch from @wordpress/scripts to Vite".
• "Set up separate entry points for front-end vs admin vs block editor".

Not for: Block registration, block.json structure, or Gutenberg API — use the official wp-block-development skill. PHP-side REST API — use wp-rest-api.

Method

1. Install @wordpress/scripts

npm install --save-dev @wordpress/scripts

`package.json`:

{
  "scripts": {
    "build":   "wp-scripts build",
    "start":   "wp-scripts start",
    "lint:js": "wp-scripts lint-js",
    "lint:css": "wp-scripts lint-style"
  }
}

Default entry point: src/index.js → build/index.js + build/index.asset.php.

2. Multiple entry points

Create webpack.config.js at plugin root to override the default entry:

const defaultConfig = require( '@wordpress/scripts/config/webpack.config' );

module.exports = {
    ...defaultConfig,
    entry: {
        'admin':        './src/admin/index.js',
        'frontend':     './src/frontend/index.js',
        'block-editor': './src/blocks/index.js',
        'style-admin':  './src/admin/admin.scss',
    },
};

Outputs:

build/
├── admin.js          + admin.asset.php
├── frontend.js       + frontend.asset.php
├── block-editor.js   + block-editor.asset.php
└── style-admin.css   (no .asset.php for pure CSS entry)

3. Enqueue assets correctly

The .asset.php file contains the dependency array and a content hash — always use it.

function my_plugin_enqueue_admin_assets() {
    $asset_file = plugin_dir_path( __FILE__ ) . 'build/admin.asset.php';
    if ( ! file_exists( $asset_file ) ) return;

    $asset = include $asset_file;

    wp_enqueue_script(
        'my-plugin-admin',
        plugin_dir_url( __FILE__ ) . 'build/admin.js',
        $asset['dependencies'],  // auto-includes wp-element, wp-i18n, etc.
        $asset['version'],       // content hash — cache busted on change
        true                     // in footer
    );

    wp_enqueue_style(
        'my-plugin-admin-style',
        plugin_dir_url( __FILE__ ) . 'build/style-admin.css',
        [],
        $asset['version']
    );

    // Pass PHP data to JS
    wp_localize_script( 'my-plugin-admin', 'myPluginData', [
        'ajaxUrl' => admin_url( 'admin-ajax.php' ),
        'nonce'   => wp_create_nonce( 'my_plugin_action' ),
        'apiUrl'  => rest_url( 'my-plugin/v1/' ),
    ] );
}
add_action( 'admin_enqueue_scripts', 'my_plugin_enqueue_admin_assets' );

For block assets registered via block.json — do NOT manually enqueue; WP handles it:

register_block_type( __DIR__ . '/build/my-block' ); // reads block.json automatically

4. Sass / PostCSS

@wordpress/scripts supports Sass out of the box (via webpack sass-loader). No extra config needed for .scss files imported in JS:

// src/admin/index.js
import './admin.scss';

For standalone .scss entry (CSS-only build):

// webpack.config.js entry
entry: {
    'admin-styles': './src/admin/admin.scss',
}

Output: build/admin-styles.css (no .asset.php generated for pure CSS entries — hardcode version or use filemtime()).

PostCSS config (postcss.config.js) is picked up automatically if present:

module.exports = {
    plugins: {
        autoprefixer: {},
        'postcss-custom-properties': {},
    },
};

5. Vite alternative

For non-block plugins where @wordpress/scripts dependency auto-detection isn't needed:

npm install --save-dev vite @vitejs/plugin-legacy

`vite.config.js`:

import { defineConfig } from 'vite';
import legacy from '@vitejs/plugin-legacy';

export default defineConfig( {
    plugins: [ legacy( { targets: [ 'defaults', 'ie >= 11' ] } ) ],
    build: {
        outDir: 'build',
        rollupOptions: {
            input: {
                admin: 'src/admin/index.js',
                frontend: 'src/frontend/index.js',
            },
            output: {
                entryFileNames: '[name].js',
                chunkFileNames: '[name]-[hash].js',
                assetFileNames: '[name].[ext]',
            },
        },
    },
} );

Caveat: Vite does not generate .asset.php. Manage WP script dependencies manually, or use wp-scripts for anything that imports @wordpress/* packages (they must be externals).

6. Externals — don't bundle WordPress packages

@wordpress/scripts automatically externalises all @wordpress/* imports (they're on the global wp object). If you use a custom webpack config, preserve this:

const defaultConfig = require( '@wordpress/scripts/config/webpack.config' );
// defaultConfig already has the correct externals — spread it, don't replace it
module.exports = { ...defaultConfig, entry: { ... } };

Never import { useState } from 'react' in WP code — import from @wordpress/element:

import { useState, useEffect } from '@wordpress/element';

7. .gitignore and production builds

node_modules/
build/

Include build/ in the SVN/release zip but NOT in git. In the release workflow (wp-plugin-release + wp-org-submission), run npm run build before zipping.

CI build step for GitHub Actions:

- uses: actions/setup-node@v4
  with:
    node-version: '20'
    cache: 'npm'
- run: npm ci
- run: npm run build

8. Reuse a dependency's bundled library instead of vendoring your own

When a plugin you already hard-depend on (e.g. EDD, WooCommerce) ships a front-end library you need — Tom Select, Select2, Choices, flatpickr — enqueue its copy rather than vendoring a second one. Saves bundle size and a maintenance surface, at the cost of coupling to the host's file paths.

function my_plugin_enqueue_tom_select(): bool {
    if ( ! defined( 'EDD_PLUGIN_URL' ) ) {
        return false; // dependency not active — caller falls back to native <select>
    }
    $url = EDD_PLUGIN_URL;
    $dir = defined( 'EDD_PLUGIN_DIR' ) ? EDD_PLUGIN_DIR : '';
    $js  = 'assets/vendor/js/tom-select.complete.min.js';
    $css = 'assets/build/css/admin/chosen.min.css'; // host's TS skin lives here

    // Guard the paths so a host restructure degrades gracefully, never fatals.
    if ( $dir && ( ! file_exists( $dir . $js ) || ! file_exists( $dir . $css ) ) ) {
        return false;
    }
    $ver = defined( 'EDD_VERSION' ) ? EDD_VERSION : MY_PLUGIN_VERSION;
    wp_enqueue_script( 'my-plugin-tom-select', $url . $js, [], $ver, true );
    wp_enqueue_style( 'my-plugin-tom-select', $url . $css, [], $ver );
    return true;
}
// Make your own script depend on it only when present:
$dep = my_plugin_enqueue_tom_select() ? [ 'my-plugin-tom-select' ] : [];
wp_enqueue_script( 'my-plugin-admin', $assets . 'js/admin.js', $dep, MY_PLUGIN_VERSION, true );

Rules that make this hold up:

• Build against the host's own constant/handle, not a hardcoded URL into another plugin's directory. Prefer reusing a registered handle (wp_enqueue_script('edd-tom-select')) when the host registers it on all admin pages; if registration is page-scoped or order-dependent, register your own handle pointing at the bundled file (as above) for deterministic loading.
• Always degrade. Return a flag; init JS behind if (typeof TomSelect !== 'undefined'); leave the markup a real <select> so it works with the library absent.
• Initialise in JS, don't fight the host's skin in markup. For a remote/AJAX field, give the library a load callback hitting your wp_ajax_* endpoint and sync any hidden companion field (e.g. a stored label) on change.
• Expect to override the host's styling. The bundled skin is themed for the host. Re-skin the library's classes (.ts-control, .ts-dropdown, etc.) to your design system. WordPress admin skins carry version-gated, high-specificity selectors — EDD's body[class*="branch-7"] rules (WP 6.7+) out-specify a plain .my-wrap scope — so targeted !important is often required to win, and load your stylesheet after the host's.

9. Don't fix a bug inside a regenerated vendor/

When the bug lives in a Composer dependency under vendor/, check two things before editing the vendor file:

1. Is `vendor/` gitignored? git check-ignore vendor/<pkg>/file.php — if it prints the path, git won't track your edit (so it can't reach a PR).
2. Does the release/deploy workflow run `composer install`? grep -rn "composer install" .github/workflows — the WP.org deploy action and most CI regenerate vendor/ from composer.lock, overwriting any hand-edit.

If both are true, a vendor edit is futile — it never reaches the shipped zip. Never rely on it. Fix it in tracked consumer code instead (config you pass into the library, a hook/filter, an unhook), or patch the dependency upstream and run composer update so the new version is locked.

Real case: a bundled marketing library phoned home via wp_remote_post(), guarded by '' !== $hash. The hash was supplied from the plugin's own tracked bootstrap, so emptying it there tripped the library's guard and killed the call — surviving the deploy-time composer install that a vendor-file edit would not.

Notes

• When borrowing a host plugin's bundled library, pin nothing about its internal version; treat the file paths as the contract and guard them (see §8). Document the coupling in the PR so a host upgrade that moves the files is easy to trace.
• Always use npm ci (not npm install) in CI — respects package-lock.json exactly.
• @wordpress/scripts pins its webpack/babel versions; don't add conflicting webpack or babel-loader to devDependencies.
• For TypeScript: @wordpress/scripts supports .ts/.tsx out of the box — just rename files and add tsconfig.json.
• Minimum Node version for @wordpress/scripts v27+: Node 20.
• Use wp-scripts lint-js and wp-scripts lint-style in CI alongside PHPCS (wp-coding-standards) for full code quality coverage.

References

• references/block-json-patterns.md — block.json full schema reference: attributes, supports, style variations, view scripts, and interactivity API flags
• references/enqueue-patterns.md — WordPress asset enqueue patterns with .asset.php dependency management, conditional loading, deferred scripts, and inline data
• references/webpack-config.md — @wordpress/scripts webpack configuration: extending defaults, custom entry points, aliasing, and build output patterns