seal/freeze single object properties and detect

sealFreezeSingleProperty.js

Object.sealProperty = function(object, property) {
  var pd = Object.getPropertyDescriptor(object, property) || {value: undefined};
  pd.configurable = false;
  return Object.defineProperty(object, property, pd);
};

Object.freezeProperty = function(object, property) {
  var pd = Object.getPropertyDescriptor(object, property) || {value: undefined};
  pd.configurable = false;
  pd.writable = false;
  return Object.defineProperty(object, property, pd);
};

// add property parameter
Object.isSealed = function(object, property) {
  
  if(arguments.length >= 2)
  {
    var pd = Object.getOwnPropertyDescriptor(object, property);
    return !!pd && !pd.configurable;
  }
  else {
    // existing behavior
  }

};

// add property parameter
Object.isFrozen = function(object, property) {
  
  if(arguments.length >= 2)
  {
    var pd = Object.getOwnPropertyDescriptor(object, property);
    return !!pd && !pd.configurable && !(("value" in pd) && pd.writable);
  }
  else {
    // existing behavior
  }

};