MyImages=new Array();
    MyImages[0]='assets/images/banners/usacm_banner.jpg';
    MyImages[1]='assets/images/banners/sccafd_banner.jpg';
    MyImages[2]='assets/images/banners/nhraps_banner.jpg';

    function newImage() 
    {
        document.getElementById("mainImage").setAttribute("src", MyImages[Math.round(Math.random()*2)])
    }