延迟函数

var delayFn={
    flag:+new Date().getTime(),
    mt:null,
    set:function(fn,delaytime){
        var self=this,
            now=+new Date().getTime(),
            fc=now-self.flag;
        (fc>delaytime)&&(clearTimeout(self.mt),self.mt=window.setTimeout(function(){fn.call(null)},500),self.flag=now);
    }
}