DOM Manipulation: append, prepend, replaceWith, remove

gistfile1.js

function append(content, element) {
    var element = element || document.body;
    element.appendChild(content);
}
function prepend(content, element) {
    var element = element || document.body;
    var firstNode = element.firstChild;
    element.insertBefore(content, firstNode);
}
function replaceWith(newNode, oldNode) {
    var parent = oldNode.parentNode;
    parent.replaceChild(newNode, oldNode);
}
function remove(node) {
    node.parentNode.removeChild(node);
}