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fix(optimize): replace load event listeners in JS Delay mode #1031

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fix(optimize): replace load event listeners in JS Delay mode #1031

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996ba50
fix(optimize): replace load event listeners in JS Delay mode
faisalahammad Aug 7, 2026
fafdff0
fix(optm): correct @since and add 8.0 changelog for JS Delay load events
faisalahammad Aug 10, 2026
b02282e
fix(optm): skip event rewrite for excluded scripts
faisalahammad Aug 10, 2026
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1 change: 1 addition & 0 deletions readme.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -259,6 +259,7 @@ You can report security bugs through the Patchstack Vulnerability Disclosure Pro

= 8.0 - Coming soon 2026 =
* 🌱**OptiMax** OptiMax to maximize the page score.
* **Optimize** Fixed JS Delay mode not executing `load` event listeners. (#629)

= 7.9 - Aug 5 2026 =
* **Cloud** Changed Health service to run asynchronously, resuming through WP cron when the cloud defers the request.
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29 changes: 22 additions & 7 deletions src/optimize.cls.php
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Expand Up @@ -88,15 +88,14 @@ public function init() {
if ($this->cfg_js_defer == 2) {
add_filter(
'litespeed_optm_cssjs',
function ( $con, $file_type ) {
if ($file_type == 'js') {
$con = str_replace('DOMContentLoaded', 'DOMContentLiteSpeedLoaded', $con);
// $con = str_replace( 'addEventListener("load"', 'addEventListener("litespeedLoad"', $con );
function ( $con, $file_type, $src ) {
if ($file_type == 'js' && !Utility::str_hit_array($src, $this->cfg_js_defer_exc)) {
$con = $this->_replace_js_events( $con );
}
return $con;
},
20,
2
3
);
}

Expand Down Expand Up @@ -1005,8 +1004,8 @@ private function _js_inline_defer( $con, $attrs = false, $minified = false ) {
if ($this->cfg_js_defer === 2) {
// Drop type attribute from $attrs
$attrs = Utility::remove_attr( $attrs, 'type' );
// Replace DOMContentLoaded
$con = str_replace('DOMContentLoaded', 'DOMContentLiteSpeedLoaded', $con);
// Replace DOMContentLoaded and load event listeners
$con = $this->_replace_js_events( $con );
return '<script' . $attrs . ' type="litespeed/javascript">' . $con . '</script>';
// return '<script' . $attrs . ' type="litespeed/javascript" src="data:text/javascript;base64,' . base64_encode( $con ) . '"></script>';
// return '<script' . $attrs . ' type="litespeed/javascript">' . $con . '</script>';
Expand All @@ -1015,6 +1014,22 @@ private function _js_inline_defer( $con, $attrs = false, $minified = false ) {
return '<script' . $attrs . ' src="data:text/javascript;base64,' . base64_encode($con) . '" defer></script>';
}

/**
* Replace JS DOMContentLoaded and load event listeners for JS Delay mode
*
* @since 8.0
*/
private function _replace_js_events( $con ) {
if ( empty( $con ) || ! is_string( $con ) ) {
return $con;
}

$con = str_replace( 'DOMContentLoaded', 'DOMContentLiteSpeedLoaded', $con );
$con = preg_replace( '/(?<!\.)\b(window\.|document\.)?addEventListener\(\s*([\'"])load\2/', '$1addEventListener($2DOMContentLiteSpeedLoaded$2', $con );
$con = preg_replace( '/((?:\$|jQuery)\(\s*(?:window|document)\s*\)\s*\.on\(\s*)([\'"])load(?=[.\s\'"])/', '$1$2DOMContentLiteSpeedLoaded', $con );
return $con;
}

/**
* Replace ESI to JS inline var (mainly used to avoid nonce timeout)
*
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