metasync / code-minification / class-js-defer-delay.php

class-js-defer-delay.php in Search Atlas SEO – OTTO AI SEO Automation for WordPress trunk, at code-minification/class-js-defer-delay.php

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1	<?php
2	/**
3	* Metasync_JS_Defer_Delay
4	* Orchestrates JS defer/async/delay for non-essential scripts.
5	*
6	* @package Search Atlas SEO
7	* @copyright Copyright (C) 2021-2025, Search Atlas Group - support@searchatlas.com
8	* @since 2.5.23
9	*/
10
11	if (!defined('ABSPATH')) {
12	exit;
13	}
14
15	class Metasync_JS_Defer_Delay {
16
17	/** @var array */
18	private $settings;
19
20	/** @var array Handles that must never be deferred or delayed. */
21	private $defer_excluded_handles = [];
22
23	/** @var array Explicit handles to delay. */
24	private $delay_handles = [];
25
26	/** @var array URL patterns that trigger delay. */
27	private $delay_patterns = [];
28
29	/** @var bool Whether the delay loader has been enqueued. */
30	private $loader_enqueued = false;
31
32	/** @var bool Whether JS delay is active for this request. */
33	private $has_delayed_scripts = false;
34
35	/** @var array Handles never to defer/delay (core + OTTO). */
36	private static $system_excluded = [
37	'jquery',
38	'jquery-core',
39	'jquery-migrate',
40	'wp-i18n',
41	'wp-hooks',
42	'wp-element',
43	'wp-polyfill',
44	'admin-bar',
45	'metasync-tracker',
46	'metasync',
47	];
48
49	public function __construct(array $settings) {
50	$this->settings = $settings;
51
52	// Parse defer exclusions
53	$user_excludes = array_filter(
54	array_map('trim', explode(',', $settings['js_defer_exclude_handles'] ?? ''))
55	);
56	$this->defer_excluded_handles = array_unique(array_merge(self::$system_excluded, $user_excludes));
57
58	// Parse delay handles
59	$this->delay_handles = array_filter(
60	array_map('trim', explode(',', $settings['js_delay_handles'] ?? ''))
61	);
62
63	// Parse delay URL patterns
64	$this->delay_patterns = array_filter(
65	array_map('trim', explode(',', $settings['js_delay_patterns'] ?? ''))
66	);
67
68	if (!is_admin()) {
69	// Priority 20: after OTTO defer at priority 10
70	add_filter('script_loader_tag', [$this, 'process_script_tag'], 20, 3);
71	add_action('wp_footer', [$this, 'maybe_output_loader'], 999);
72	}
73	}
74
75	/**
76	* Process each script tag for defer or delay.
77	*
78	* @param string $tag The script tag.
79	* @param string $handle The script handle.
80	* @param string $src The script source URL.
81	* @return string Modified script tag.
82	*/
83	public function process_script_tag(string $tag, string $handle, string $src): string {
84	// Never modify excluded handles
85	if ($this->is_excluded($handle)) {
86	return $tag;
87	}
88
89	// Check if this script should be delayed
90	if ($this->should_delay($handle, $src)) {
91	return $this->delay_script($tag, $src);
92	}
93
94	// Otherwise, defer if enabled
95	if (!empty($this->settings['enable_js_defer'])) {
96	return $this->defer_script($tag);
97	}
98
99	return $tag;
100	}
101
102	/**
103	* Add defer attribute to a script tag.
104	*/
105	private function defer_script(string $tag): string {
106	// Don't add if already has defer or async
107	if (strpos($tag, 'defer') !== false \|\| strpos($tag, 'async') !== false) {
108	return $tag;
109	}
110
111	return str_replace(' src=', ' defer src=', $tag);
112	}
113
114	/**
115	* Convert a script tag to a delayed script.
116	* Replaces type with metasync/delayed and src with data-metasync-src.
117	*/
118	private function delay_script(string $tag, string $src): string {
119	$this->has_delayed_scripts = true;
120
121	// Replace type attribute or add one
122	if (preg_match('/type\s=\s["\'][^"\']*["\']/', $tag)) {
123	$tag = preg_replace('/type\s=\s["\'][^"\']*["\']/', 'type="metasync/delayed"', $tag);
124	} else {
125	$tag = str_replace('<script ', '<script type="metasync/delayed" ', $tag);
126	}
127
128	// Replace src with data-metasync-src
129	$tag = preg_replace(
130	'/\ssrc\s=\s(["\'])(' . preg_quote($src, '/') . ')\1/',
131	' data-metasync-src=$1$2$1',
132	$tag
133	);
134
135	// Fallback: simpler replacement
136	if (strpos($tag, 'data-metasync-src') === false) {
137	$tag = str_replace("src='" . $src . "'", "data-metasync-src='" . $src . "'", $tag);
138	$tag = str_replace('src="' . $src . '"', 'data-metasync-src="' . $src . '"', $tag);
139	}
140
141	return $tag;
142	}
143
144	/**
145	* Output the delay loader script if we have delayed scripts.
146	*/
147	public function maybe_output_loader(): void {
148	if (!$this->has_delayed_scripts \|\| $this->loader_enqueued) {
149	return;
150	}
151
152	$this->loader_enqueued = true;
153	?>
154	<script id="metasync-delay-loader">
155	(function(){
156	var loaded=false;
157	var events=['mousemove','scroll','keydown','touchstart','click'];
158	function load(){
159	if(loaded)return;
160	loaded=true;
161	events.forEach(function(e){document.removeEventListener(e,load);});
162	document.querySelectorAll('script[type="metasync/delayed"]').forEach(function(el){
163	var s=document.createElement('script');
164	s.src=el.getAttribute('data-metasync-src');
165	if(el.id)s.id=el.id;
166	s.defer=true;
167	el.parentNode.replaceChild(s,el);
168	});
169	}
170	events.forEach(function(e){document.addEventListener(e,load,{once:true,passive:true});});
171	setTimeout(load,5000);
172	})();
173	</script>
174	<?php
175	}
176
177	/**
178	* Check if a handle is excluded from defer/delay.
179	*/
180	private function is_excluded(string $handle): bool {
181	return in_array($handle, $this->defer_excluded_handles, true);
182	}
183
184	/**
185	* Check if a script should be delayed (not just deferred).
186	*/
187	private function should_delay(string $handle, string $src): bool {
188	if (empty($this->settings['enable_js_delay'])) {
189	return false;
190	}
191
192	// Check explicit delay handles
193	if (in_array($handle, $this->delay_handles, true)) {
194	return true;
195	}
196
197	// Check URL pattern matches
198	if (!empty($src)) {
199	foreach ($this->delay_patterns as $pattern) {
200	if (!empty($pattern) && strpos($src, $pattern) !== false) {
201	return true;
202	}
203	}
204	}
205
206	return false;
207	}
208	}
209