Get post meta in enqueued js file

You can send variables to your script with wp_localize_script:

wp_enqueue_script( 'some_handle' );

global $post;
$my_meta = get_post_meta( $post->ID, 'my_meta', true );

$array = array( 
    'my_meta' => $my_meta
);

wp_localize_script( 'some_handle', 'object_name', $array );

You can then use the var in your script like:

object_name.my_meta