Acceder a propiedad y subpropiedad anidada de javascript con notacion de punto

• https://stackoverflow.com/questions/6491463/accessing-nested-javascript-objects-with-string-key
• https://stackoverflow.com/questions/8051975/access-object-child-properties-using-a-dot-notation-string

  function getDescendantProp(obj, desc) {
      var arr = desc.split(".");
      while(arr.length && (obj = obj[arr.shift()]));
      return obj;
  }
  
  console.log(getDescendantProp(r, "b.b2"));
  //-> 99