uss oop for nav check

app/assets/javascripts/admin/utils/services/navigation_check.js.coffee

@@ -1,37 +1,46 @@
 angular.module("admin.utils")
   .factory "NavigationCheck", ($window, $rootScope) ->
-    callbacks = []
+    new class NavigationCheck
+      callbacks = []
+      constructor: ->
+        if $window.addEventListener
+          $window.addEventListener "beforeunload", @onBeforeUnloadHandler
+        else
+          $window.onbeforeunload = @onBeforeUnloadHandler
 
-    # Action for regular browser navigation.
-    onBeforeUnloadHandler = ($event) ->
-      message = getMessage()
-      if message
-        ($event or $window.event).preventDefault()
+        $rootScope.$on "$locationChangeStart", @locationChangeStartHandler
+
+
+      # Action for regular browser navigation.
+      onBeforeUnloadHandler: ($event) =>
+        message = @getMessage()
+        if message
+          ($event or $window.event).preventDefault()
+          message
+
+      # Action for angular navigation.
+      locationChangeStartHandler: ($event) =>
+        message = @getMessage()
+        if message and not $window.confirm(message)
+          $event.stopPropagation() if $event.stopPropagation
+          $event.preventDefault() if $event.preventDefault
+          $event.cancelBubble = true
+          $event.returnValue = false
+
+      # Runs callback functions to retreive most recently added non-empty message.
+      getMessage: ->
+        message = null
+        message = callback() ? message for callback in callbacks
         message
 
-    # Action for angular navigation.
-    locationChangeStartHandler = ($event) ->
-      message = getMessage()
-      if message and not $window.confirm(message)
-        $event.stopPropagation() if $event.stopPropagation
-        $event.preventDefault() if $event.preventDefault
-        $event.cancelBubble = true
-        $event.returnValue = false
+      register: (callback) =>
+        callbacks.push callback
 
-    # Runs callback functions to retreive most recently added non-empty message.
-    getMessage = ->
-      message = null
-      message = callback() ? message for callback in callbacks
-      message
+      clear: =>
+        if $window.addEventListener
+          $window.removeEventListener "beforeunload", @onBeforeUnloadHandler
+        else
+          $window.onbeforeunload = null
 
-    register = (callback) ->
-      callbacks.push callback
+        $rootScope.$on "$locationChangeStart", null
 
-    if $window.addEventListener
-      $window.addEventListener "beforeunload", onBeforeUnloadHandler
-    else
-      $window.onbeforeunload = onBeforeUnloadHandler
-
-    $rootScope.$on "$locationChangeStart", locationChangeStartHandler
-
-    return register: register