// JavaScript Document

var imgDir = './img/';
var ext = '.gif';

function prelimg(){
	var imgnArr = new Array(
							'pre_btn',
							'pre_btn_on',
							'ap_btn',
							'ap_btn_on'
							);
	
	var imgCnt = imgnArr.length;
	
	var imgBuff = new Array(imgCnt);
	var imgSrcn = new Array(imgCnt);
	for(i=0;i<imgCnt;i++){
		
		imgBuff[i] = new Image();
		imgSrcn[i] = imgDir + imgnArr[i] + ext;
		imgBuff[i].src = imgSrcn[i];
			
		}
	}
	
	
function rov(imgn,srcn){
	document.getElementById(imgn).src = imgDir + srcn + ext;
	}