The new Date of problem is handled under ie8

<script> 
function getDays(strDateStart,strDateEnd){ 
  var strSeparator = "-";  
  var oDate1; var oDate2; var iDays; 
  oDate1= strDateStart.split(strSeparator); 
  oDate2= strDateEnd.split(strSeparator); 
  var strDateS = new Date(oDate1[0], oDate1[1]-1, oDate1[2]); 
  var strDateE = new Date(oDate2[0], oDate2[1]-1, oDate2[2]); 
  iDays = parseInt(Math.abs(strDateS - strDateE ) / (1000*24*3600)) 
  return iDays ; 
}  
alert(getDays('2014-02-26','2014-08-18')) 
</script>