anchor.diff:      The app no longer fails and the list of names displays again in the browser.
   
     :marked
  -    When there is no `selectedHero`, the `ngIf` directive removes the hero detail HTML from the DOM.
  +    When there is no selected hero, the `ngIf` directive removes the hero detail HTML from the DOM.
       There are no hero detail elements or bindings to worry about.
   
       When the user picks a hero, `selectedHero` becomes defined and
  
positive.code:   :marked
      ### Hide the empty detail with ngIf
  
      When the app loads, the `selectedHero` is undefined and won't be defined until you click a hero's name.
      Angular can't display properties of the undefined `selectedHero` and throws the following error,
      visible in the browser's console:
  
  
negative.code: 
    :marked
      The template still refers to the old `hero` property.
      Bind to the new `selectedHero` property instead as follows:
  
  
    +makeExample('toh-2/ts/src/app/app.component.1.html', 'selectedHero-details', 'app.component.ts (template excerpt)')(format='.')
  