Watch state params changes

app.slim

  body body-locker="true"

body_locker.coffee

angular.module("shared").directive "bodyLocker", ($rootScope, $state) ->
  link: (scope, element, attrs) ->
    $rootScope.$on '$stateChangeSuccess', (event, state) ->
      if $state.current.data?.modal
        element.addClass("body--locked")
      else
        element.removeClass("body--locked")

router.coffee

angular.module('HR').config ($stateProvider, $urlRouterProvider, env) ->

  $urlRouterProvider.otherwise("/")

  $stateProvider
    .state('rewards/edit', {
      url: "/rewards/edit/:id"
      controller: "RewardFormCtrl"
      templateUrl: env.templates["hr/rewards/edit.html"]
    })
    .state('rewards/edit.image', {
      templateUrl: env.templates["hr/rewards/_image.html"]
      data: { modal: true }
    })