Inject_js_async.md

Facebook style of injecting js file

<div id="km-root"></div>
<script>(function(d, s, id) {
  var js, kjs = d.getElementsByTagName(s)[0];
  if (d.getElementById(id)) return;
  js = d.createElement(s); js.id = id;
  js.src = "//cdn.atomex.net/static/js/pxs/6701/ast.js";
  kjs.parentNode.insertBefore(js, kjs);
}(document, 'script', 'komli-js'));</script>

Load js async

(function(doc, script) {
    var js, 
        fjs = doc.getElementsByTagName(script)[0],
        add = function(url, id) {
            if (doc.getElementById(id)) {return;}
            js = doc.createElement(script);
            js.src = url;
            id && (js.id = id);
            fjs.parentNode.insertBefore(js, fjs);
        };
    // Facebook SDK
    add('//connect.facebook.net/en_US/all.js', 'facebook-jssdk');
}(document, 'script'));

Reference https://css-tricks.com/thinking-async/

load_img_pixel.md

Loading image pixel

var img = d.createElement("img");
if("style" in img)
  img.style.display = "none";
img.src = "http://pixel.gif";