How to load a script dynamically

(function() { var script = document.createElement('script'); script.async = true; var useSSL = 'https:' == document.location.protocol; script.src = (useSSL ? 'https:' : 'http:') + '//' + 'TARGET_URL'; var node = document.getElementsByTagName('script')0; node.parentNode.insertBefore(script, node); })();