Get the value of an object property where the property is a string consisting either of the name or changed hierarchy

obj-get-prop.js

console.clear();
var obj = {
    namespace: {
        foo: "123"
    }
};

function getPropVal(obj, prop) {
  var levels = prop.split(".");
  if (levels.length === 1) { return obj[levels[0]]; }
  isUndefined = false;
  var val = levels.reduce(function (prev, next) {
    if (prev[next] === undefined) { isUndefined = true; }
    return prev[next] || {};  
  }, obj);
  if (isUndefined) {
      return;
  } else {
      return val;
  }
}


console.log(getPropVal({}, "namespace.foo")); //undefined
console.log(getPropVal(obj, "namespace.foo")); //123

function setPropVal(obj, prop, val) {
  var levels = prop.split(".");
  var len = levels.length;
  var current = obj;
  levels.forEach(function (level, index) {
    if (index === len - 1) {
      current[level] = val;
    }
    if (current[level] === undefined) {
      current[level] = {};
    }
    current = current[level];
  });
}

var obj2 = {};

setPropVal(obj, "namespace.foo", "456");

console.log(obj.namespace.foo); //456

setPropVal(obj2, "namespace.foo", "456");

console.log(obj2.namespace.foo); //456