The Object.entries()
method returns an array of a given object's own enumerable string-keyed property [key, value]
pairs, in the same order as that provided by a for...in
loop (the difference being that a for-in loop enumerates properties in the prototype chain as well). The order of the array returned by Object.entries() does not depend on how an object is defined. If there is a need for certain ordering then the array should be sorted first like Object.entries(obj).sort((a, b) => b[0].localeCompare(a[0]));
.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
Syntax
Object.entries(obj)
Parameters
obj
- The object whose own enumerable string-keyed property
[key, value]
pairs are to be returned.
Return value
An array of the given object's own enumerable string-keyed property [key, value]
pairs.
Description
Object.entries()
returns an array whose elements are arrays corresponding to the enumerable string-keyed property [key, value]
pairs found directly upon object
. The ordering of the properties is the same as that given by looping over the property values of the object manually.
Examples
const obj = { foo: 'bar', baz: 42 }; console.log(Object.entries(obj)); // [ ['foo', 'bar'], ['baz', 42] ] // array like object const obj = { 0: 'a', 1: 'b', 2: 'c' }; console.log(Object.entries(obj)); // [ ['0', 'a'], ['1', 'b'], ['2', 'c'] ] // array like object with random key ordering const anObj = { 100: 'a', 2: 'b', 7: 'c' }; console.log(Object.entries(anObj)); // [ ['2', 'b'], ['7', 'c'], ['100', 'a'] ] // getFoo is property which isn't enumerable const myObj = Object.create({}, { getFoo: { value() { return this.foo; } } }); myObj.foo = 'bar'; console.log(Object.entries(myObj)); // [ ['foo', 'bar'] ] // non-object argument will be coerced to an object console.log(Object.entries('foo')); // [ ['0', 'f'], ['1', 'o'], ['2', 'o'] ] // returns an empty array for any primitive type, since primitives have no own properties console.log(Object.entries(100)); // [ ] // iterate through key-value gracefully const obj = { a: 5, b: 7, c: 9 }; for (const [key, value] of Object.entries(obj)) { console.log(`${key} ${value}`); // "a 5", "b 7", "c 9" } // Or, using array extras Object.entries(obj).forEach(([key, value]) => { console.log(`${key} ${value}`); // "a 5", "b 7", "c 9" });
Converting an Object
to a Map
The new Map()
constructor accepts an iterable of entries
. With Object.entries
, you can easily convert from Object
to Map
:
const obj = { foo: 'bar', baz: 42 }; const map = new Map(Object.entries(obj)); console.log(map); // Map { foo: "bar", baz: 42 }
Iterating through an Object
Using Array Destructuring, you can iterate through objects easily.
const obj = { foo: 'bar', baz: 42 }; Object.entries(obj).forEach(([key, value]) => console.log(`${key}: ${value}`)); // "foo: bar", "baz: 42"
Polyfill
To add compatible Object.entries
support in older environments that do not natively support it, you can find a demonstrational implementation of Object.entries in the tc39/proposal-object-values-entries (if you don't need any support for IE), a polyfill in the es-shims/Object.entries repositories, or you can use the simple, ready to deploy polyfill listed below.
if (!Object.entries) { Object.entries = function( obj ){ var ownProps = Object.keys( obj ), i = ownProps.length, resArray = new Array(i); // preallocate the Array while (i--) resArray[i] = [ownProps[i], obj[ownProps[i]]]; return resArray; }; }
For the above polyfill code snippet, if you need support for IE < 9, then you will also need an Object.keys polyfill (such as the one found on the Object.keys
page).
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript Latest Draft (ECMA-262) The definition of 'Object.entries' in that specification. |
Draft | Initial definition. |
ECMAScript 2017 (ECMA-262) The definition of 'Object.entries' in that specification. |
Standard |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
entries | Chrome Full support 54 | Edge Full support 14 | Firefox Full support 47 | IE No support No | Opera Full support 41 | Safari Full support 10.1 | WebView Android Full support 54 | Chrome Android Full support 54 | Firefox Android Full support 47 | Opera Android Full support 41 | Safari iOS Full support 10.3 | Samsung Internet Android Full support 6.0 | nodejs
Full support
7.0.0
|
Legend
- Full support
- Full support
- No support
- No support
- User must explicitly enable this feature.
- User must explicitly enable this feature.