Function hasBuiltInToString

lib/internal/util/inspect.js:2701–2744

(value)

}

function hasBuiltInToString(value) {
  // Prevent triggering proxy traps.
  const getFullProxy = false;
  const proxyTarget = getProxyDetails(value, getFullProxy);
  if (proxyTarget !== undefined) {
    if (proxyTarget === null) {
      return true;
    }
    return hasBuiltInToString(proxyTarget);
  }

  let hasOwnToString = ObjectPrototypeHasOwnProperty;
  let hasOwnToPrimitive = ObjectPrototypeHasOwnProperty;

  // Count objects without `toString` and `Symbol.toPrimitive` function as built-in.
  if (typeof value.toString !== 'function') {
    if (typeof value[SymbolToPrimitive] !== 'function') {
      return true;
    } else if (ObjectPrototypeHasOwnProperty(value, SymbolToPrimitive)) {
      return false;
    }
    hasOwnToString = returnFalse;
  } else if (ObjectPrototypeHasOwnProperty(value, 'toString')) {
    return false;
  } else if (typeof value[SymbolToPrimitive] !== 'function') {
    hasOwnToPrimitive = returnFalse;
  } else if (ObjectPrototypeHasOwnProperty(value, SymbolToPrimitive)) {
    return false;
  }

  // Find the object that has the `toString` property or `Symbol.toPrimitive` property
  // as own property in the prototype chain.
  let pointer = value;
  do {
    pointer = ObjectGetPrototypeOf(pointer);
  } while (!hasOwnToString(pointer, 'toString') &&
    !hasOwnToPrimitive(pointer, SymbolToPrimitive));

  // Check closer if the object is a built-in.
  const descriptor = ObjectGetOwnPropertyDescriptor(pointer, 'constructor');
  return descriptor !== undefined &&
    typeof descriptor.value === 'function' &&
    builtInObjects.has(descriptor.value.name);
}

function returnFalse() {
  return false;