var jBeginTime,jEndTime;

function jBegin(){
	now=new Date();
	jBeginTime=now.getTime();
}

function jEnd(){
	now=new Date();
	jEndTime=now.getTime();
}

function genImage(start,end) {
    this.length = end-start+1
    for (var i=start ; i<=end ; i++) {
        this[i] = new Image()
    }
    return this
}