var banner = new Array();

banner[0]=[url=https://servimg.com/image_preview.php?i=126&u=18267811][img]https://i.servimg.com/u/f72/18/26/78/11/images17.jpg[/img][/url];
banner[1]=[url=https://servimg.com/image_preview.php?i=127&u=18267811][img]https://i.servimg.com/u/f72/18/26/78/11/academ10.jpg[/img][/url];

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