function randomImage() {
var img_name = new Array('img-commercial-02.jpg','img-commercial-03.jpg','img-commercial-04.jpg','img-commercial-05.jpg');

var l = img_name.length;

var rnd_no = Math.round((l-1)*Math.random());
	document.getElementById('imgGlobal').src="resources/img/"+img_name[rnd_no];
}