Add attributes to Wordpress Enqueueing/ Registering Scripts

enqueue_script_attribute.php

<?php
/**
 * Add attributes to script while enqueueing/registering.
 *
 * @param string $tag    whole script tag of current enqueueing script.
 * @param string $handle current enqueuing script handler.
 *
 * @return string
 */
function filter_script_loader_tag( $tag, $handle ) {
	
	$attributes = array(
		'async' => true,
	);
	
	// Add each attribute to tag if it's not been added already.
	foreach ( $attributes as $key => $value ) {
		if ( ! preg_match( ":\s$key(=|>|\s):", $tag ) ) {
			if ( true === $value ) {
				$attribute_string = sprintf( ' %s', esc_attr( $key ) );
			} else {
				$attribute_string = sprintf( ' %s="%s"', esc_attr( $key ), esc_attr( $value ) );
			}
			$tag = preg_replace(
				':(?=></script>):',
				$attribute_string,
				$tag,
				1
			);
		}
	}
}

add_filter( 'script_loader_tag', 'filter_script_loader_tag', 10, 2 );