Get Plugin Asset URL or Full DIR Path

plugins-url-abspath-asset.php

<?php
/**
 * Get the plugin directory for a path.
 *
 * @param string $path The path to the file.
 *
 * @return string The new path.
 */
public static function get_plugin_dir( $path = '' ) {
	$dir = rtrim( plugin_dir_path( __FILE__ ), '/' );
	if ( ! empty( $path ) && is_string( $path ) ) {
		$dir .= '/' . ltrim( $path, '/' );
	}
	return $dir;
}

/**
 * Return a plugin URL path.
 *
 * @param string $path Path to the file.
 *
 * @return string URL to to the file.
 */
public static function get_plugin_url( $path = '' ) {
	$dir = rtrim( plugin_dir_url( __FILE__ ), '/' );
	if ( ! empty( $path ) && is_string( $path ) ) {
		$dir .= '/' . ltrim( $path, '/' );
	}
	return $dir;
}

Assume that __FILE__ is on the root file. Include dirname if in a subdirectory.