JSFiddle - React, Tailwind, and code Playground

by Julien Etienne

JavaScript

// Helpers.
const type = Symbol.toStringTag; // Hidden property.
const isType = (value, type) => ({}).toString.call(value).includes(type);

// Define animals.
const object1 = {
  animal: 'Snake'
};
const object2 = {
  animal: 'Dolphin'
};
const object3 = {
  animal: 'Eagle'
};

object1[type] = 'Reptile';
object2[type] = 'Mammal';
object3[type] = 'Bird';

const animals = [object1, object2, object3];

animals.forEach(animal => {
  if (isType(animal, 'Mammal') === true) {
    console.info(animal);
    console.info(Object.keys(animal));
    console.log(animals.Mammal === undefined);
  }
});