get unlinked nodes for a given node (aka. forEachUnlinkedNode)

forEachUnlinkedNode.js

forEachUnlinkedNode : function (nodeId, callback) {
    var node = this.getNode(nodeId),
            i,
            link,
            linkedNodeId;

    if (node && node.links && typeof callback === 'function') {
        var linkedNodes = [];
        for (i = 0; i < node.links.length; ++i) {
            link = node.links[i];
            linkedNodeId = link.fromId === nodeId ? link.toId : link.fromId;
            linkedNodes.push(nodes[linkedNodeId]);
        }
        var unlinkedNodes = _.difference(nodes, linkedNodes); // array diff of linkedNodes from all nodes 
        for (i = 0; i < unlinkedNodes.length; ++i) {
            callback(unlinkedNodes[i]);
        }
   }
},