Utility script for use with Drupal Menus

gistfile1.js

/**
 * Utility to add a className to the menu block menu item that would be the 
 * current node's parent, based on the url path.
 * @param {array} cores, an array containing the 1st parts of url segments 
 *                       associated with individual menu blocks where the 
 *                       index maps to the id of the menu block such that 
 *                       for a[n] there will exist an element with the id 
 *                       block-menu_block-n.
 * @author Noah Feldman
 * @copyright 2011
 */

// UPDATED because apparently I can't count, how embarrassing

(function (cores) {
var uri = window.location.href.split('/'),
    segments = [], menu, links, link;

// cross-browser indexOf for arrays, strings, nodeLists, etc.
function indexOf(item, list) {
    if (!!list.indexOf)
        return list.indexOf(item);
    for (var i = 0, len = list.length; i < len; i++)
        if (list[i] === item) return i;
    return -1;
}
// bare-bones filter implementation
function filter(list, func) {
    if (list && typeof list.length != 'number')
        throw TypeError('cannot iterate object that does not have a length');
    for (var i = 0, len = list.length, ret = []; i < len; i++) {
        var x = list[i];
        func.call(null, x, i, list) && ret.push(x);
    }
    return ret;
}
 
// create an array of URL segments from the root relative URL
for (var i = 2, j = 0, len = uri.length; ++i < len; ++j)
    segments[j] = uri[i];

// and figure out the ID that should match the current menu block's ID
// this was shortened to the first part of the segment as the least likely
// to change if friendly urls are tweaked...may be a false assumptio
menu = document.getElementById('block-menu_block-' + indexOf(segments[0].substring(0, segments[0].indexOf('-')), cores));

if (menu) {
    // get all links beneath it
    link = menu.getElementsByTagName('a');
    // and winnow them down to 1 link or nothing
    for (var ct = 0, len = segments.length; ct++ < len;) {
        links = link;
        link = filter(links, function(el) {
            var t = RegExp("^" + segments[ct]),
                h = el.getAttribute('href');
            if (/^http/.test(h))
                h = el.getAttribute('href', 2);
            h = h.substring(1).split('/');
            if (h[ct] && t.test(h[ct]))
                return el;
        });
        if (link.length == 1)
            return link[0].className += link[0].className ? ' active' : 'active';
    }
}
}([0,0,'patient','research','professional','special','community','overview']));