randomImageDisplay = {
	getRamdomNum:function(){
		return Math.floor(Math.random()*randomImageDisplay.arrayLength);
		},
	showImage:function(n){
		displayBannerName = randomImageDisplay.srcArray[n];
		document.getElementById(displayBannerName).style.display="block";
		},
	init:function(array){
		randomImageDisplay.srcArray =array;
		randomImageDisplay.arrayLength = array.length;
		var displayBannerType_Num = randomImageDisplay.getRamdomNum();
		randomImageDisplay.showImage(displayBannerType_Num);
		}
	};