while(count++)和while(count--)

Question

• Loop operations are optimized by using while(count--) { ... }
  • - this means that in order to keep the same order of execution as addition we have to add
  • items to the array at the beginning (unshift) instead of at the end (push)

这是angular.js中Scope里面的一段注释
为啥while(count--)比while(count++)更优，感觉不出来区别啊，一个是从头往尾遍历，一个是从尾往头遍历，is there any different?

Answer 1

while(count--)的话可以保证不会死循环，因为count值为0的时候，while循环不会再执行, 而while(count++)的话必须要使用break才可以。