gistfile1.js

<script type='text/javascript'>
// For js file
loadjscssfile("http://example.com/js/rssfeedreader.js", "js");
// For css file
loadjscssfile("http://example.com/css/rsspage.css", "css");

function loadjscssfile(filename, filetype){
    if (filetype == "js") { //if filename is a external JavaScript file
        var fileref = document.createElement('script')
        fileref.setAttribute("type", "text/javascript")
        fileref.setAttribute("src", filename)
    }
    else
    if (filetype == "css") { //if filename is an external CSS file
        var fileref = document.createElement("link")
        fileref.setAttribute("rel", "stylesheet")
        fileref.setAttribute("type", "text/css")
        fileref.setAttribute("href", filename)
    }
    document.getElementsByTagName("head")[0].appendChild(fileref)
}
</script>