yay underscore

new.js

    // hit the /parents API endpoint
    $.getJSON(parentGeoAPI)
        .done(function(results) {
            var parents = results['parents'];
            // list of unique parent sumlev types, maintaining order
            var parentRelations = _.uniq(_.pluck(parents, 'sumlevel'));
            // collect parents into individual sumlev groups
            var parentGroups = _.groupBy(parents, function(d) {
                return d.sumlevel;
            });
            // for each parent sumlev type ...
            var parentLinkSets = _.map(parentRelations, function(r) {
                // ... compile a set of links to individual profile pages
                var parentLinkSet = _.map(parentGroups[r], function(v, k) {
                    return '<a href="/profiles/' + v.geoid + '/">' + v.display_name + '</a>';
                });
                var numParents = parentLinkSet.length;
                // if more than one of a sumlev type, group behind reveal link
                if (numParents > 1) {
                    return '<a href="#" class="link-reveal">'+numParents+' '+ sumlevMap[r]['plural'] +'</a><span class="hidden">'+parentLinkSet.join(', ')+'</span>';
                } else {
                    // just one of this sumlev type, so add it to list
                    return parentLinkSet;
                }
            })
            // push the whole thing into the header box ... thingy
            parentLinkContainer.html(parentLinksPrefix + parentLinkSets.join(', '));
        });

old.js

    // hit the /parents API endpoint
    $.getJSON(parentGeoAPI)
        .done(function(results) {
            var parents = results['parents']
                parentGroups = {},
                parentRelations = [],
                parentLinks = [];

            // loop through the results so we can group by sumlev type
            parents.forEach(function(d) {
                var relation = d.relation;
                // build ordered list of unique parent sumlev types
                if (parentRelations.indexOf(relation) == -1) {
                    parentRelations.push(relation)
                }
                // collect parents into sumlev groups
                parentGroups[d.relation] = parentGroups[d.relation] || {};
                parentGroups[d.relation][d.geoid] = d;
            })
            
            // loop through the parent sumlev types
            parentRelations.forEach(function(r) {
                var parentKeys = Object.keys(parentGroups[r]),
                    numParents = parentKeys.length,
                    parentLinkSet = [];
                    
                // create basic profile links for each parent...
                parentKeys.forEach(function(k) {
                    var d = parentGroups[r][k];
                    parentLinkSet.push('<a href="/profiles/' + d.geoid + '/">' + d.display_name + '</a>');
                })
                // ... and group them into comma-separated list
                parentLinkSet = parentLinkSet.join(', ');
                
                // hide sumlev groups with more than one parent,
                // and provide trigger that unhides them
                if (numParents > 1) {
                    parentLinks.push('<a href="#" class="link-reveal">'+numParents+' '+ r +'</a><span class="hidden">'+parentLinkSet+'</span>');
                } else {
                    parentLinks.push(parentLinkSet);
                }
            })
            
            parentLinkContainer.html(parentLinksPrefix + parentLinks.join(', '));
        });