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
orMap
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
Specification |
---|
ECMAScript Language Specification # sec-object.fromentries |
Browser compatibility
BCD tables only load in the browser