deep-problem-data.js

function deepCopy(obj) {
 return JSON.parse(JSON.stringify(obj)); // serialize -> deserialize -> unique clone
}

function copy(obj) {
   let clone = Array.isArray(obj) ? [] : {};

   for (let key in obj) {
       let value = obj[key];
       clone[key] = (typeof value === "object") ? copy(value) : value;
   }

   return clone;
}

const original = {
  a: new Date(),
  b: NaN,
  c: new Function(),
  d: undefined,
  e: function(){},
  f: Number,
  g: false,
  h: Infinity
}

const firstCopy = deepCopy(original); 
// JSON-safe { a: "2019-04-30T19:18:47.026Z", b: null, g: false, h: null }

const secondCopy = copy(original); 
// { a: {}, b: NaN, c: ƒ( ), d: undefined, e: ƒ (), f: Number(), g: false, h: Infinity }
// But we see that complex structures (Date) we still could not correct copy

// original
const animals = {
  zebra: {
    food: ['leaves', 'bark'],
    name: 'zebra'
  },
  panda: {
    food: [],
    name: 'panda'
  }
};

const newAnimals = copy(animals); // deep clone

newAnimals.panda.food.push('leaves');

console.log(animals.panda.food);     // [ ]
console.log(newAnimals.panda.food);  // [ 'leaves' ]