contact-form-7-conditional-enqueues.php

<?php
/**
 * Contact Form 7 Conditional Enqueues WordPress Plugin.
 *
 * @package   CF7_Conditional_Enqueues
 * @author    Weston Ruter, Google
 * @license   GPL-2.0-or-later
 * @copyright 2023 Google Inc.
 *
 * @wordpress-plugin
 * Plugin Name: Contact Form 7 Conditional Enqueues
 * Description: Prevent enqueueing JS and CSS for Contact Form 7 unless there is a form on the page. This is a mini plugin to implement the changes suggested in <a href="https://github.com/rocklobster-in/contact-form-7/issues/1278">contact-form-7#1278</a>.
 * Plugin URI: https://gist.github.com/westonruter/af6ce5699e4b5576f51a7cd901b80152
 * Version: 0.1.0
 * Author: Weston Ruter
 * Author URI: https://weston.ruter.net/
 * License: GNU General Public License v2 (or later)
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 * Update URI: https://gist.github.com/westonruter/af6ce5699e4b5576f51a7cd901b80152
 */

namespace CF7_Conditional_Enqueues;

/**
 * Required CF6 version.
 *
 * Version in which the wpcf7_shortcode_callback action was introduced.
 *
 * @var string
 */
const REQUIRED_CF7_VERSION = '5.8.1';

/**
 * Enqueue scripts if not already enqueued.
 */
function conditionally_enqueue_scripts() {
	if ( ! did_action( 'wpcf7_enqueue_scripts' ) ) { // Prevent double-enqueueing when multiple forms present.
		wpcf7_enqueue_scripts();
	}
}

/**
 * Enqueue styles if not already enqueued.
 */
function conditionally_enqueue_styles() {
	if ( ! did_action( 'wpcf7_enqueue_styles' ) ) { // Prevent double-enqueueing when multiple forms present.
		wpcf7_enqueue_styles();
	}
}

/**
 * Add shortcode callbacks to enqueue scripts and styles.
 */
function add_shortcode_callbacks() {
	// The wpcf7_shortcode_callback action was added in CF7 version 5.8.1.
	if ( ! defined( 'WPCF7_VERSION' ) || version_compare( WPCF7_VERSION, REQUIRED_CF7_VERSION, '<' ) ) {
		return;
	}

	add_filter( 'wpcf7_load_js', '__return_false', PHP_INT_MAX );
	add_filter( 'wpcf7_load_css', '__return_false', PHP_INT_MAX );

	add_action( 'wpcf7_shortcode_callback', __NAMESPACE__ . '\conditionally_enqueue_scripts' );
	add_action( 'wpcf7_shortcode_callback', __NAMESPACE__ . '\conditionally_enqueue_styles' );
}

/*
 * The wpcf7_shortcode_callback action fires when the form is rendered. This happens naturally on the frontend but it
 * also can happen in the block editor when the post data is obtained from the REST API via
 * block_editor_rest_api_preload(). However, the wpcf7_enqueue_scripts() and wpcf7_enqueue_styles() functions are
 * not loaded in the admin context. For this reason, callbacks are only added when we're certain to be on the frontend.
 */
add_action( 'template_redirect', __NAMESPACE__ . '\add_shortcode_callbacks' );