为什么ng-class没有使用setTimeout更新？角

I have a function 'highlightBookmark' that should change the background color of a list item after 2 seconds. But it doesn't work!!! It changes 'li' background only if the function is called by click event. It doesn't change it automatically after time is out, even if it actually calls the function.I have a function 'highlightBookmark' that shou