deepPick whitlisted nodes from an object

deepPick

function getElement(obj, element) {
    var res = {};
    var nodes = element.split('.');
    var currentSelf = res;
    var currentObj = obj;
    if (nodes.length === 1) {
        res[element] = obj[element];
        return res;
    } else {
        nodes.slice(0, nodes.length -1).forEach(function(key) {
            currentSelf[key] = {};
            currentSelf = currentSelf[key];
            currentObj = currentObj[key];
        });
        var lastKey = nodes[nodes.length - 1];
        currentSelf[lastKey] = currentObj[lastKey];
    }
    return res;
}

function merge(self) {
    self = self || {};
    var args = Array.prototype.slice.call(arguments, 1);
    args.forEach(function(other) {
        Object.keys(other).map(function(key) {
            self[key] = other[key];
        });
    });
    return self;
}

function deepPick(obj, whitelist) {
    return whitelist.reduce(function(p, c) {
        return merge(p, getElement(obj, c));
    }, {});
}

// simple tests
var obj = {a:1, b:2,c:3,d:{e:4, f:{g:8, z:0}, h: [1,2,3], i: [{j:1}, {k:2}]}}
// Object {a: 1, b: 2, c: 3, d: Object}

var res = deepPick(obj, ["a", "d.i"])
// Object {a: 1, d: Object}

// should contain an array
res.d.i
// [Objectj: 1__proto__: Object, Object]

res = deepPick(obj, ["a", "d.f.g"])
//Object {a: 1, d: Object}

// shouldn't contain z
res.d.f
//Object {g: 8}