Object.fromEntries()

The Object.fromEntries() method transforms a list of key-value pairs into an object.

Syntax

Object.fromEntries(iterable);

Parameters

iterable

An iterable such as Array or Map or other objects implementing the iterable protocol.

Return value

A new object whose properties are given by the entries of the iterable.

Description

The Object.fromEntries() method takes a list of key-value pairs and returns a new object whose properties are given by those entries. The iterable argument is expected to be an object that implements an @@iterator method, that returns an iterator object, that produces a two element array-like object, whose first element is a value that will be used as a property key, and whose second element is the value to associate with that property key.

Object.fromEntries() performs the reverse of Object.entries().

Examples

Converting a Map to an Object

With Object.fromEntries, you can convert from Map to Object:

const map = new Map([ ['foo', 'bar'], ['baz', 42] ]);
const obj = Object.fromEntries(map);
console.log(obj); // { foo: "bar", baz: 42 }

Converting an Array to an Object

With Object.fromEntries, you can convert from Array to Object:

const arr = [ ['0', 'a'], ['1', 'b'], ['2', 'c'] ];
const obj = Object.fromEntries(arr);
console.log(obj); // { 0: "a", 1: "b", 2: "c" }

Object transformations

With Object.fromEntries, its reverse method Object.entries(), and array manipulation methods, you are able to transform objects like this:

const object1 = { a: 1, b: 2, c: 3 };

const object2 = Object.fromEntries(
  Object.entries(object1)
  .map(([ key, val ]) => [ key, val * 2 ])
);

console.log(object2);
// { a: 2, b: 4, c: 6 }

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
fromEntries
73
79
63
No
60
12.1
73
73
63
No
12.2
11.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries