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Object.entries Javascript Object.entries() and Object.values() Methods in JavaScript

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The Object.entries() and Object.values() methods were introduced to JavaScript Object constructor with the release of ECMAScript 2017 (ES8). Let us have a quick look at these useful methods.

Object.entries() Method

The Object.entries() method takes an object as argument and returns an array with arrays of key-value pairs:

const birds = {
    owl: '🦉',
    eagle: '🦅',
    duck: '🦆'

const entries = Object.entries(birds);

// [['owl', '🦉'], ['eagle', '🦅'], ['duck', '🦆']]
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The order of the array element do not depend on how the object was defined. The order is same as that provided by a loop.

Iterating through an Object

We can use Object.entries() to iterate over object as well:

// using `for...of` loop
for (const [key, value] of Object.entries(birds)) {
    console.log(`${key}: ${value}`);

// owl: 🦉
// eagle: 🦅
// duck: 🦆

// using array destructuring
Object.entries(birds).forEach(([key, value]) => console.log(`${key}: ${value}`));

// owl: 🦉
// eagle: 🦅
// duck: 🦆
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Converting an Object to a Map

Since the Map constructor also takes an iterable of entries to initialize a map object, the Object.entries() method can be used to create a map from an object:

const map = new Map(Object.entries(birds));

console.log(map.size); // 3
console.log(map.has('owl')); // true
console.log(map.get('duck')); // 🦆
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Object.values() Method

The Object.values() method works very much like Object.entries(), but only returns the values of the own enumerable string-keyed properties in the same order as provided by the loop:

const foods = {
    cake: '🍰',
    pizza: '🍕',
    candy: '🍬',
    icecream: '🍨'

const values = Object.values(foods);

// ['🍰', '🍕', '🍬', '🍨']
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Both Object.values() and Object.entries() do not follow the prototype chain and only iterate through the properties that are directly added to the given object. They also ignore all non-enumerable properties as well:

Object.defineProperty(foods, 'sushi', {
    value: '🍣',
    writable: true,
    configurable: true,
    enumerable: false


// ['🍰', '🍕', '🍬', '🍨']
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Converting an Object to Set

Since the Set constructor accepts an iterable, with Object.values(), we can easily convert an Object to a Set:

const set = new Set(Object.values(foods));

console.log(set.size); // 4
console.log(set.has('🍨')); // true
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Latest comments (4)

mauroporras profile image
Mauro Porras

There is also the Object.keys() method:

const object1 = {
  a: 'somestring',
  b: 42,
  c: false

// expected output: Array ["a", "b", "c"]

bradtaniguchi profile image

I legit did not know you could do:

const map = new Map(Object.entries(birds));

I thought I was being sly for doing it manually with a single line reduce:

const map = Object.entries(birds).reduce(
  (map, [key, value]) => map.set(key, value),
  new Map()

Good to know! I will have to use the shorter version the next time I need an es6 map 😉

adam_cyclones profile image
Adam Crockett

You might be interested in objectFromEntries which can conver Maps into objects or reconstruct entries.

mauroporras profile image
Mauro Porras

Thanks. Check this example from the MDN:

const entries = new Map([
  ['foo', 'bar'],
  ['baz', 42]

const obj = Object.fromEntries(entries);

// expected output: Object { foo: "bar", baz: 42 }