var banner = new Array();

banner[0]='https://img7.hostingpics.net/pics/866137ban.jpg';
banner[1]='https://img7.hostingpics.net/pics/830555ban1.jpg';
banner[2]='https://img7.hostingpics.net/pics/830689ban2.jpg';


document.getElementById('i_logo').src= 
banner[Math.floor(Math.random()*banner.length)];