Enqueue your script and use `wp_localize_script` to pass data.

    function wpd_scripts() {
    		
    	wp_enqueue_script(
    		'wpd_script',
    		get_template_directory_uri() . '/js/script.js',
    		null,
    		null,
    		false
    	);
    	
    	wp_localize_script(
    		'wpd_script',
    		'WPD',
    		array(
    			'template_dir' => get_template_directory_uri()
    		)
    	);
    
    }
    add_action( 'wp_enqueue_scripts', 'wpd_scripts' );

You can then use `WPD.template_dir` in your script to get the value you set in PHP.