Ember.js: sorting with computed properties

gistfile1.js

export default Ember.Controller.extend({
  posts: [], // Filled by real world data by the route
  postsSorting: ['name'],
  postsSortingDesc: ['name:desc'],
  
  sortedPosts: Ember.computed.sort('posts', 'postsSorting'),
  sortedPostsDesc: Ember.computed.sort('posts', 'postsSortingDesc'),
  customSortedPost: Ember.computed.sort('posts', function(a, b) {
    // return a negative when a < b, 0 when a = b, and a positive when a > b
  })
});