puntillo.js

var puntillo = (function () {
    function get(parent, nested, defValue) {
        return splitMy(nested)
                .reduce(function(acc, current) {
                    return acc ? acc[current] : defValue;
                }, parent);
    }

    function set(parent, nested, defValue) {
        return splitMy(nested)
                .reduce(function(acc, current, index, arr) {
                    acc[current] = typeof acc[current] !== 'undefined' ?
                        acc[current] :
                        (index === arr.length -1 ? defValue : {});
                    return acc[current];
                }, parent)

    }

    function splitMy (nested) {
        return nested.split(/[\.\["'\]]/).filter(Boolean);
    }

    var methods = {
        get: get,
        set: set
    };

    return (function (fn, parent, nested, defValue) {
        return methods[fn].apply(null, [].slice.call(arguments, 1))
    });
})();


var ns = {a:{b:{c:0}}};

console.log(puntillo('get', ns, 'a.b.d.e')) // undefined
console.log(puntillo('get', ns, 'a.b.d.e', 3)) // 3
console.log(puntillo('set', ns, 'a.b.d.e.h', 7)); // 7  -> creates namespace a.b.d.e.h === 7