자바스크립트 날짜 사이에 속하는지 확인

function fn_amongDay(startDate, endDate){
var pass = false;
var date = new Date();
date = new Date(date.getFullYear(), date.getMonth(), date.getDate());
var startDate = new Date(startDate);
var endDate = new Date(endDate);

var diffCnt = endDate.getTime() - startDate.getTime();

diffCnt = diffCnt / (24 * 60 * 60 * 1000);

for(var i=0; i<=diffCnt; i++){
var tmpDate = new Date(startDate.getFullYear(), startDate.getMonth(), (startDate.getDate() + i));
if(date.getTime() == tmpDate.getTime()){
pass = true;
diffCnt = i;
}
}
return pass;
}