var how_many_ads = 10; var now = new Date() var sec = now.getSeconds() var ad = sec % how_many_ads; switch(ad) { case 0: content = '

'; break; case 1: content = '

'; break; case 2: content = '

'; break; case 3: content = '

'; break; case 4: content = '

'; break; case 5: content = '

'; break; case 6: content = '

'; break; default: content = '

'; } end='>'; //if (ad < 3) //{ document.write(content);