conditional-loading-block-assets.php

<?php
// conditionally load sal.js assets
function lmdm_animation_scripts(){
	if(is_singular()) {
		$blocks = parse_blocks(do_shortcode(get_post(get_the_ID())->post_content));
		if(is_array($blocks)){
			foreach($blocks as $block){
				if(isset($block["attrs"]["effect"]) && !empty($block["attrs"]["effect"])){
					wp_enqueue_style('saljs-style', get_stylesheet_directory() . '_js/saljs/sal.css');
					wp_enqueue_script('lmdm-saljs', get_stylesheet_directory() . '_js/saljs/sal.js', null, "1.0");
					wp_add_inline_script("lmdm-saljs", "window.addEventListener('load', () => { sal({ threshold: 0.5 }); });");
				}
			}
		}
	}
}
add_action( 'wp_enqueue_scripts', 'lmdm_animation_scripts',100);