_get.js

function _get(parent, nested) {
    return typeof nested === 'string' ?
        (typeof parent === 'object' &&
        nested
            .split(/[\.\["'\]]/)
            .filter(Boolean)
            .reduce(function(acc, current) {
                return acc && acc[current]
            }, parent)) :
        parent;
}

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

console.log('get(ns, "")',_get(ns, '')) // Object {a: Object}
console.log("get(ns, 'a.b.')", _get(ns, 'a.b.')) // Object {c: 0}
console.log("get(ns, 'a.b.d')", _get(ns, 'a.b.d')) // undefined
console.log("get(ns, 'a.b.c')", _get(ns, 'a.b.c')) // 0
console.log("get(ns, 'u.b.c')", _get(ns, 'u.b.c')) // undefined

console.log("get(ns, 'a['b'].c')", _get(ns, 'a["b"].c')) // 0
console.log("get(ns, 'a.b['c']')", _get(ns, 'a.b["c"]')) // 0
console.log("get(ns, 'a['b']['c']')", _get(ns, 'a["b"]["c"]')) // 0
console.log("get(ns, 'a.b['forgery']')", _get(ns, 'a.b["forgery"]')) // undefined


console.log("get(ns, 2)",_get(ns, 2)) // Object {a: Object}
console.log("get(ns, function(){})", _get(ns, function(){})) // Object {a: Object}

console.log("get(ns)", _get(ns)) // Object {a: Object}
console.log("get('')", _get('')) // ""
console.log("get(false)", _get(false)) // false