anchor.diff:    disappears as we move out.
   
     运行本应用并确认：当把鼠标移到`p`上的时候，背景色就出现了，而移开的时候，它消失了。
  +  
   figure.image-display
     img(src="/resources/images/devguide/attribute-directives/highlight-directive-anim.gif" alt="Second Highlight")
   
  
positive.code: +makeExcerpt('src/app/app.component.ts', 'class', '')
  
  :marked
    Here are the harness and directive in action.下面是测试程序和指令的动图。
  figure.image-display
    img(src="/resources/images/devguide/attribute-directives/highlight-directive-v2-anim.gif" alt="Highlight v.2")
  
  
negative.code:   directive to set an element's background color
    when the user hovers over that element. You can apply it like this:
    
    本章展示了如何创建一个简单的属性型指令 _myHighlight_ ，当用户把鼠标悬停在一个元素上时，改变它的背景色。你可以这样用它：
  
  +makeExcerpt('src/app/app.component.1.html', 'applied', '')
  
  