// JavaScript Document
var imgdir = './img/';
var ext = '.jpg'

function prel(){
	var imgnamesArr = new Array(
								'n1',
								'n2',
								'n3',
								'n4',
								'n5'
								);
	
	var imgCnt = imgnamesArr.length;
	var imgSrc = new Array(imgCnt);
	var imgTbl = new Array(imgCnt);
	for(i=0;i<imgCnt;i++){
		imgSrc[i] = imgdir + imgnamesArr[i];
		imgTbl[i] = new Image();
		imgTbl[i].src = imgSrc[i];
		}
	
	}
	
function rov(imgN,srcN,act){
	srcN = imgdir + srcN;
	if(act == 'over'){
		document.images[imgN].src = srcN + '_on' + ext;
		}else if(act == 'out'){
			document.images[imgN].src = srcN + ext;
			}
	}