some people said the change event of checkbox can not trigger in the ie7 or ie8,that‘s not true.
this event can trigger in the ie7 or ie8 ,but you can not get the correct checked property value right now,you only can get right value when this event is triggered next time.
to resolve this problem,my advice is you‘d better to don‘t use change event of checkbox if your main clients are lower version ie.and use click event to instead of change event.
there is issue about change event of checkbox in the ie8 oe ie7
原文：http://www.cnblogs.com/langu/p/3951011.html