function fileLinks() {
    var fileLink;
    if (document.getElementsByTagName('a')) {
        for (var i = 0; (fileLink = document.getElementsByTagName('a')[i]); i++) {
            if (fileLink.href.indexOf('.pdf') != -1) {
                fileLink.setAttribute('target', '_blank');
                fileLink.className = 'pdfLink';
            }
            if (fileLink.href.indexOf('.doc') != -1) {
                fileLink.setAttribute('target', '_blank');
                fileLink.className = 'docLink';
            }
            if (fileLink.href.indexOf('.zip') != -1) {
                fileLink.setAttribute('target', '_blank');
                fileLink.className = 'zipLink';
            }
        }
    }
}
window.onload = function() {
    fileLinks();
}

a:hover {
    text-decoration: none;
}
.pdfLink {
    padding-right: 19px;
    background: url(pdf.gif) no-repeat 100% .5em;
}
.docLink {
    padding-right: 19px;
    background: url(doc.gif) no-repeat 100% .5em;
}
.zipLink {
    padding-right: 17px;
    background: url(zip.gif) no-repeat 100% .5em;
}