util-ex/src/is/type/primitive.js

Browser-friendly enhanced util fully compatible with standard node.js

export function isPrimitive(arg) {
  return arg === null || typeof arg === 'boolean' || typeof arg === 'number' || typeof arg === 'string' || typeof arg === 'symbol' ||
  // ES6 symbol
  typeof arg === 'undefined';
};
export default isPrimitive;