var banner = new Array();

banner.push('https://i.servimg.com/u/f68/10/08/46/90/so3tjj10.png');
banner.push('https://i.servimg.com/u/f64/12/54/56/48/nee10.png');
banner.push('https://i.servimg.com/u/f64/12/54/56/48/e10.png');

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