Loading gists async without jquery

embed-gist.js

(function(){
    var gists = document.getElementsByTagName('gist');
    function embed(id, file, i, tag) {
        window['gist_embed_'+i] = function(gist) {
            console.log(gist);
            if (!document.getElementById('gist_css_'+id)) {
                var css = document.createElement('link');
                css.id = 'gist_css_'+id;
                css.rel = 'stylesheet';
                css.href = gist.stylesheet;
                document.head.appendChild(css);
            }
            var tmp = document.createElement('div');
            tmp.innerHTML = gist.div;
            tag.parentNode.replaceChild(tmp.firstChild, tag);
        };
        var url = 'https://gist.github.com/'+id+'.json?callback=gist_embed_'+i;
        if(file) {
            url += '&file='+file;
        }
        var script = document.createElement('script');
        script.type = 'text/javascript';
        script.src = url;
        document.head.appendChild(script);
    }
    for(var i=0; i<gists.length; i++) {
        var id = gists[i].getAttribute('data-id');
        var file = gists[i].getAttribute('data-file');
        if(id) {
            gists[i].innerHTML = '<a href="https://gist.github.com/'+id+'">Loading gist...</a>';
            embed(id, file, i, gists[i]);
        }
    }
})();

Based on https://gist.github.com/JeanSebTr/4138162.

Usage: <gist data-id="f0c2d35ba43bc3490ff0" data-file="embed-gist.js"></gist>