[WP] Replace Underscore with Lodash

class-dj-use-lodash.php

<?php
/**
 * Use `Lodash` as the drop-in replacement for Underscore in WordPress.
 *
 * This script uses the `CDNJS` API to ensure the latest version of Lodash is
 * always retrieved. By default, Lodash will run only on the WordPress frontend
 * unless the `$sitewide` parameter is set to `true`.
 *
 * @author Davey Jacobson <djacobson@usarugby.org>
 * @package Davey_Jacobson
 * @subpackage Use_Lodash
 */
if ( ! defined( 'ABSPATH' ) ) exit; // exit if directly accessed

class DJ_Use_Lodash {

    /**
     * This current version of this class.
     *
     * @var string
     */
    private $version = '1.0.0';

    /**
     * The appropriate scope to load Lodash in.
     *
     * @var string
     */
    public $scope;

    /**
     * Transient for the API retrieval.
     *
     * @var string
     */
    public $transient = 'use_lodash_';

    /**
     * Primary constructor.
     *
     * @param bool [$sitewide=false] Optional. Set to `true` if you want to
     *                               use Lodash across all of WordPress.
     * @return DJ_Use_Lodash
     */
    public function __construct( $sitewide = false ) {
        $this->transient .= md5( $this->version );
        $this->scope     = $sitewide && is_admin() ? 'admin' : 'wp';

        add_action( "{$this->scope}_enqueue_scripts", array( $this, 'replace_underscore_with_lodash' ), 10 );
    }

    /**
     * Replace the default version of `Underscore` with `Lodash` in WordPress.
     *
     * @since 1.0.0
     *
     * @uses {@see 'wp_deregister_script'}
     * @uses {@see 'wp_register_script'}
     * @uses {@see 'wp_enqueue_script'}
     */
    public function replace_underscore_with_lodash() {

        // Prevent WordPress from loading Underscore.
        wp_deregister_script( 'underscore' );

        // Get Lodash from CDNJS.
        $lodash = $this->get_lodash_from_cdnjs();

        /*
         * Re-register the `underscore` hook with Lodash as its script. This ensures that
         * Lodash will be used as THE drop-in replacement for Underscore all across WordPress.
         */
        wp_register_script( 'underscore', $lodash['url'], null, $lodash['version'], true );
        wp_enqueue_script( 'underscore' );

    }

    /**
     * Query the `CDNJS` API and return the lastest version of Lodash.
     *
     * @access private
     *
     * @since 1.0.0
     *
     * @return array   Lodash filepath and version from `CDNJS` API.
     */
    private function get_lodash_from_cdnjs() {

        // All files on CDNJS are found in this path.
        define( 'CDNJS', 'https://cdnjs.cloudflare.com/ajax/libs' );

        // This will hold what's needed by WordPress.
        $lodash = array();

        // This is our current cached-for-the-year request to the CDNJS API.
        $data = get_transient( $this->transient );

        // Check if we've cached this request and cache it if needed.
        if ( false === $data ) {
            // Lodash is named `lodash.js` on CDNJS.
            $lodash_on_cdnjs = 'lodash.js';

            // The CDNJS API endpoint.
            $cdnjs_api_endpoint = "https://api.cdnjs.com/libraries/{$lodash_on_cdnjs}?fields=name,filename,version";

            // Send request to CDNJS.
            $request = wp_remote_get( $cdnjs_api_endpoint );
            if ( is_wp_error( $request ) ) {
                return $request->get_error_message();
            }

            // If no errors were found, retrieve the CDNJS response.
            $response = wp_remote_retrieve_body( $request );
            if ( is_wp_error( $response ) ) {
                return $response->get_error_message();
            }

            // If no error were found, parse the response from CDNJS.
            $data = json_decode( $response );

            // Set the transient for this retrieval.
            set_transient( $this->transient, $data, YEAR_IN_SECONDS );
        }

        // Ensure you're grabbing the file you requested.
        if ( $lodash_on_cdnjs === $data->name ) {
            // Build the Lodash URL from the CDNJS response.
            $lodash_url = CDNJS . "/{$lodash_on_cdnjs}/{$data->version}/{$data->filename}";
            // Remember the array we made on line 78?
            $lodash['url']     = $lodash_url;
            $lodash['version'] = $data->version;
        }

        // Return the Lodash components needed for WordPress.
        if ( ! empty( $lodash['url'] ) ) {
            return $lodash;
        }

    }

}

new DJ_Use_Lodash();