var imgDir = "image/";
var imgExt = ".gif";

var filelist = new Array(
	"menu00","menu100",
	"menu01","menu101",
	"menu02","menu102",
	"menu03","menu103",
	"menu04","menu104",
	"menu05","menu105",
	"menu06","menu106",
	"menu07","menu107"
);
var theImages = new Array();
function preLoad () {
	for ( var i = 0; i < filelist.length; i++ ) {
		theImages[ i ] = new Image();
		theImages[ i ].src = imgDir + filelist[ i ] + imgExt;
	}
}
preLoad();
function chgImg( imgObjName, imgName ){
	document.images[ imgObjName ].src = imgDir + imgName + imgExt;
}