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 }
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Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Object.fromEntries' in that specification. |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
fromEntries | Chrome Full support 73 | Edge Full support 79 | Firefox Full support 63 | IE No support No | Opera Full support 60 | Safari Full support 12.1 | WebView Android Full support 73 | Chrome Android Full support 73 | Firefox Android Full support 63 | Opera Android No support No | Safari iOS Full support 12.2 | Samsung Internet Android No support No | nodejs Full support 12.0.0 |
Legend
- Full support
- Full support
- No support
- No support