To just make the DOM API's a little cleaner is so simple in a language like JavaScript, why not just create the abstractions as you need them?

This is not something you should use in production, but just a quick example:

    function setAttr (attr, val) {
      return function (elem) { elem.setAttribute(attr, val); };
    }
    NodeList.prototype.forEach = Array.prototype.forEach;
    var $ = document.querySelectorAll.bind(document);

    $('.foo').forEach(setAttr('foo', 'bar'));