How to send back js.haml in rails

Actually, returning JS in HAML is pretty easy, just use the :plain filter and enclose anything you want evaluated in #{}.

:plain
  var appearance = $("#{escape_javascript(render(:partial => @appearance)}").effect("highlight", {color: '#E6ff00'}, 2000);
  $("#sortable").append(appearance);
  $("#new_appearance")[0].reset();

Do not use the :javascript filter as it will enclose everything in a tag which is unnecessary.

If you need to use some logic, just put the :plain inside the nesting.

- if params[:printing]
  :plain
    $('#print-view').html("#{escape_javascript(render 'print_preview')}");

Sorry ERB.