javascript下ie7，ie8的Date Bug的解决

ie9+, chrome firefox opera下 string到Date 使用  new Date("2013-01-01"); 都是ok的。

但在ie7， ie8下 返回NaN

 function parseISO8601(dateStringInRange) {  
   var isoExp = /^\s*(\d{4})-(\d\d)-(\d\d)\s*$/,  
       date = new Date(NaN), month,  
       parts = isoExp.exec(dateStringInRange);  
  
   if(parts) {  
     month = +parts[2];  
     date.setFullYear(parts[1], month - 1, parts[3]);  
     if(month != date.getMonth() + 1) {  
       date.setTime(NaN);  
     }  
   }  
   return date;  
 } 

 parseISO8601('2016-10-01');