# ablocks/trunk/includes/performance/delay-js.php

aBlocks – Gutenberg Blocks, User Dashboard Builder, Popup Builder, Form Builder & Animation Builder, version trunk. 106 lines.

- Page: https://pluginprobe.com/plugins/ablocks/trunk/code/includes/performance/delay-js.php
- Raw: https://pluginprobe.com/plugins/ablocks/trunk/raw/includes/performance/delay-js.php
- Modified: 2026-09-08T12:29:06+00:00

Line numbers below start at 1. Link to a line or a range by appending a fragment to the
page URL, for example `https://pluginprobe.com/plugins/ablocks/trunk/code/includes/performance/delay-js.php#L10-L20`.

```php
<?php
namespace ABlocks\Performance;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

use ABlocks\Helper;

/**
 * Performance Suite — delay JavaScript until the first user interaction.
 *
 * The aBlocks combined frontend script is emitted in a non-executing form and
 * swapped in on the first interaction (scroll/key/pointer/touch) or after a
 * fallback timeout, cutting main-thread work during initial load (INP/TBT).
 *
 * Opt-in via `perf_delay_js`. The handles affected are filterable so it stays
 * scoped to aBlocks scripts (third-party JS is never touched).
 */
class DelayJs {

	public static function init() {
		if ( is_admin() ) {
			return;
		}
		$enabled = (bool) apply_filters(
			'ablocks/perf/perf_delay_js',
			(bool) Helper::get_settings( 'perf_delay_js', false )
		);
		if ( ! $enabled ) {
			return;
		}
		// Never delay scripts for a logged-in editor viewing the frontend, so
		// building/previewing the site is unaffected; real visitors still get it.
		if ( is_user_logged_in() && current_user_can( 'edit_posts' )
			&& (bool) apply_filters( 'ablocks/perf/bypass_optimizations_for_editors', true ) ) {
			return;
		}
		$self = new self();
		// The tag rewriting is shared with consent gating; see ScriptGate.
		( new ScriptGate(
			'ablocks/delayed',
			function ( $handle ) use ( $self ) {
				return $self->should_delay( $handle );
			},
			null,
			true
		) )->hook( 20 );
		add_action( 'wp_footer', [ $self, 'print_loader' ], 99 );
	}

	private function handles() {
		return (array) apply_filters(
			'ablocks/perf/delay_js_handles',
			[ 'ablocks-blocks-combine-script' ]
		);
	}

	/**
	 * Whether a script handle should be delayed. Covers the combined per-page
	 * script (assets-generation on) and the per-block frontend scripts
	 * (assets-generation off), so delay works in both modes.
	 *
	 * @param string $handle Script handle.
	 * @return bool
	 */
	public function should_delay( $handle ) {
		if ( in_array( $handle, $this->handles(), true ) ) {
			return true;
		}
		return (bool) preg_match( '/^ablocks-.+-block-static-script$/', (string) $handle );
	}

	/**
	 * Print the tiny vanilla loader that activates delayed scripts on interaction.
	 */
	public function print_loader() {
		$timeout = (int) Helper::get_settings( 'perf_delay_js_timeout', 5000 );
		$timeout = max( 0, $timeout );
		?>
		<script id="ablocks-delay-js-loader">
		( function () {
			var loaded = false;
			var events = [ 'scroll', 'keydown', 'pointerdown', 'touchstart', 'mousemove' ];
			function load() {
				if ( loaded ) { return; }
				loaded = true;
				events.forEach( function ( e ) { window.removeEventListener( e, load ); } );
				document.querySelectorAll( 'script[type="ablocks/delayed"]' ).forEach( function ( s ) {
					var n = document.createElement( 'script' );
					var src = s.getAttribute( 'data-ablocks-src' );
					if ( src ) { n.src = src; }
					if ( s.id ) { n.id = s.id + '-delayed'; }
					document.body.appendChild( n );
				} );
			}
			events.forEach( function ( e ) { window.addEventListener( e, load, { passive: true, once: true } ); } );
			<?php if ( $timeout > 0 ) : ?>
			setTimeout( load, <?php echo (int) $timeout; ?> );
			<?php endif; ?>
		} )();
		</script>
		<?php
	}
}

```