Lazyly Load JavaScript

gistfile1.js

<script>
    function lazyLoadJavaScript() {
        var scripts = document.createElement("script"),
            jquery = document.createElement("script");
        scripts.src = "{{ source to your custom scripts }}";
        jquery.src = "//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js";
        document.body.appendChild(jquery);
        document.body.appendChild(scripts);
    }
    if (window.addEventListener)
        window.addEventListener("load", lazyLoadJavaScript, false);
    else if (window.attachEvent)
        window.attachEvent("onload", lazyLoadJavaScript);
    else window.onload = lazyLoadJavaScript;
</script>