How to make translatable JavaScript strings on your WordPress theme

Simply paste the following code into your function.php file, where you generally enqueue scripts and styles. Line 4 shows how to use the wp_localize_script() function.

function prefix_enqueue_custom_script(){
	wp_register_script( 'prefix_custom_script', plugin_dir_url( __FILE__ ) .'js/custom-script.js', array( 'jquery' ) );
        wp_enqueue_script( 'prefix_custom_script' );
        wp_localize_script( 'prefix_custom_script', 'prefix_object_name', array(
		'upload' => __( 'upload', 'textdomain' ),
		'remove' => __( 'remove', 'textdomain' )
	) );
}

Thanks to Devin for this code!