jQuery promises

application.coffee

City =
  find: (location) ->
    promise = $.Deferred()
    $.ajax '/cities',
      data: q: location
      success: (result) ->
        promise.resolve result.city
      error: ->
        promise.reject 'invalid location'
    promise

Weather =
  today: (location) ->
    promise = $.Deferred()
    $.ajax '/weather',
      data: q: location
      success: (result) ->
        promise.resolve result.weather
      error: ->
        promise.reject 'invalid location'
    promise

$('button').on 'click', (e) ->
  e.preventDefault()
  loc = $(this).data('loc')
  $.when(
    Weather.today(loc),
    City.find(loc)
  ).then (weatherResult, cityResult) ->
    $('#results').append cityResult, weatherResult