native javascript insert <script> (code or link) in DOM

exec_body_scripts.js

    function exec_body_scripts(body_el) {
        function nodeName(elem, name) {
            return elem.nodeName && elem.nodeName.toUpperCase() ===
                name.toUpperCase();
        }

        function evalScript(elem) {
            var data = (elem.text || elem.textContent || elem.innerHTML || "" ),
                script = document.createElement("script");

            if (elem.src) {
                script.src = elem.src;
            }
            script.type = "text/javascript";
            try {
                // doesn't work on ie...
                script.appendChild(document.createTextNode(data));
            } catch(e) {
                // IE has funky script nodes
                script.text = data;
            }

            body_el.appendChild(script);
        }

        // main section of function
        var scripts = [],
            script,
            children_nodes = body_el.childNodes,
            child,
            i;

        for (i = 0; children_nodes[i]; i++) {
            child = children_nodes[i];
            if (nodeName(child, "script" ) &&
                (!child.type || child.type.toLowerCase() === "text/javascript" || child.type.toLowerCase() === "application/javascript")) {
                scripts.push(child);
            } else {
                exec_body_scripts(child);
            }
        }

        for (i = 0; scripts[i]; i++) {
            script = scripts[i];
            if (script.parentNode) {script.parentNode.removeChild(script);}
            evalScript(scripts[i]);
        }
    }