js 日期相差的天数详解编程语言

function  DateDiff(sDate1,  sDate2){    //sDate1和sDate2是2006-12-18格式     
          var  aDate,  oDate1,  oDate2,  iDays     
          aDate  =  sDate1.split("-")     
          oDate1  =  new  Date(aDate[1]  +  '-'  +  aDate[2]  +  '-'  +  aDate[0])    //转换为12-18-2006格式     
          aDate  =  sDate2.split("-")     
          oDate2  =  new  Date(aDate[1]  +  '-'  +  aDate[2]  +  '-'  +  aDate[0])     
          iDays  =  parseInt(Math.abs(oDate1  -  oDate2)  /  1000  /  60  /  60  /24)    //把相差的毫秒数转换为天数    
          return  iDays + 1    
      }

var day1 = (new Date).setFullYear(2011, 7, 16); 
var day2 = (new Date).setFullYear(2011, 7, 20); 
var number_of_days = (day2 - day1) / 86400000; 
 
// 输出 4 
alert(number_of_days);  
// 将值赋予 input 
document.getElementById('days').value = number_of_days;