vralle-jquery-cdn.php

<?php
/**
 * Plugin Name:         vralle.jQuery-CDN
 * Plugin URI:          https://github.com/vralle/vralle-jquery-cdn
 * Description:         A modern way to load jQuery from CDN with a local fallback
 * Version:             1.0.0
 * Author:              V.Ralle
 * Author URI:          https://github.com/vralle/
 * License:             MIT
 * GitHub Plugin URI:   https://github.com/vralle/vralle-jquery-cdn
 * Requires WP:         4.6
 * Requires PHP:        5.6
 *
 * @package vralle-jquery-cdn
 */

namespace VralleJqueryCdn;

use function \add_action;
use function \add_filter;
use function \apply_filters;
use function \esc_url;
use function \is_admin;
use function \sprintf;
use function \wp_add_inline_script;
use function \wp_deregister_script;
use function \wp_register_script;
use function \wp_scripts;

// If this file is called directly, abort.
if ( ! defined( 'WPINC' ) ) {
	die;
}

add_action( 'plugins_loaded', __NAMESPACE__ . '\\init' );

/**
 * Register all of the needed hooks and actions.
 */
function init() {
	add_action( 'wp_enqueue_scripts', __NAMESPACE__ . '\\enqueue_scripts', 11 );
	add_filter( 'script_loader_tag', __NAMESPACE__ . '\\make_tag', 10, 3 );
}

/**
 * Load jQuery from Google CDN with a local fallback
 */
function enqueue_scripts() {
	if ( is_admin() ) {
		return;
	}
	$jquery_script = wp_scripts()->registered['jquery-core'];
	$jquery_src    = $jquery_script->src;
	$jquery_ver    = $jquery_script->ver;

	/**
	 * CDN version of jQuery
	 *
	 * @param string             Current jQuery version.
	 * @param string $jquery_ver The jQuery version used by WordPress.
	 */
	$cdn_ver = apply_filters( 'vralle_jquery_cdn_ver', '3.5.1', $jquery_ver );

	wp_deregister_script( 'jquery-core' );
	wp_deregister_script( 'jquery' );

	wp_register_script(
		'jquery-core',
		'https://ajax.googleapis.com/ajax/libs/jquery/' . $cdn_ver . '/jquery.min.js',
		array(),
		$cdn_ver,
		true
	);

	wp_register_script( 'jquery', false, array( 'jquery-core' ), $cdn_ver, true );

	$site_url = site_url();

	if ( ! $site_url ) {
		$site_url = wp_guess_url();
	}

	$fallback = sprintf(
		'(window.jQuery && jQuery.noConflict()) || document.write(\'<script src=\"%s\"><\/script>\')',
		esc_url( $site_url . $jquery_src )
	);
	wp_add_inline_script( 'jquery', $fallback );
}


/**
 * Make HTML tag
 *
 * @param string $tag    The <script> tag for the enqueued script.
 * @param string $handle The script's registered handle.
 * @param string $src    The script's source URL.
 *
 * @return string The script tag
 */
function make_tag( $tag, $handle, $src ) {
	if ( is_admin() ) {
		return $tag;
	}
	if ( 'jquery-core' === $handle ) {
		$tag = sprintf(
			'<script src="%s" crossorigin="anonymous"></script>',
			esc_url( $src )
		);
	}

	return $tag;
}