kikan = 15;      // 日数を変更する場合はこの値を適当に
icon = "new!";  // 適宜、サイズやalt属性を指定<img src='画像へのパス'>
today = new Date();
upday = new Date();
function koushin(y, m, d) {
   upday.setFullYear(y);
   m = m - 1;
   upday.setMonth(m);
   upday.setDate(d);
   difference = today.getTime() - upday.getTime();
   difference = Math.floor(difference / (1000 * 60 * 60 * 24));
   if (difference < kikan) {
      document.write(icon);
   }
} 


//function displayNewMark(){
//	if(!document.getElementsByTagName) return;
	// passage time
//	var passageTime = 24;
	// display mark
//	var mark = 'New!!';
//	var currentDate = new Date();
//	var elements = document.getElementsByTagName('span');
//	for (var i = 0, len = elements.length; i < len; i++){
//		if(elements[i].className == 'new')}
//		var time = elements[i].firstChild.nodeValue.split(':');
//		var entryDate = new Date(time[0],time[1]-1,time[2],time[3],time[4],time[5]);
//		var currentTime = (entryDate.getTime () - currentDate.getTime())/(60*60*1000);
//		currentTime = Math.ceil(currentTime);
//		if(-currentTime <= passageTime){
//			elements[i].innerHTML = mark;
//			elements[i].style.display = 'inline';
//		}
//		}
//	}
//}