A definition list accordion in three lines of CoffeeScript with jQuery

accordion.coffee

$("dl.mini-accordion dt").on "click", ->
  $(@).parent().find("dt, dd").removeClass("is-open")
  $.each [ $(@), $(@).next() ], (i, e) -> $(e).addClass("is-open")

accordion.html

<dl class="mini-accordion">
  <dt class="is-open">Item 1</dt>
  <dd class="is-open>Description 1</dd>

  <dt>Item 2</dt>
  <dd>Description 2</dd>

  <dt>Item 3</dt>
  <dd>Description 3</dd>
</dl>