var banner = new Array();

banner.push('http://s2.noelshack.com/uploads/images/8765866095723_banniereteammonkey.png');
banner.push('https://i.servimg.com/u/f68/14/88/60/81/ded03710.jpg');
banner.push('http://s2.noelshack.com/uploads/images/8765866095723_banniereteammonkey.png');

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