Object.keys()
BaselineWidely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
TheObject.keys() static method returns an array of a given object's own enumerable string-keyed property names.
Try it
const object1 = { a: "some string", b: 42, c: false,};console.log(Object.keys(object1));// Expected output: Array ["a", "b", "c"]Syntax
Object.keys(obj)Parameters
objAn object.
Return value
An array of strings representing the given object's own enumerable string-keyed property keys.
Description
Object.keys() returns an array whose elements are strings corresponding to the enumerable string-keyed property names found directly uponobject. This is the same as iterating with afor...in loop, except that afor...in loop enumerates properties in the prototype chain as well. The order of the array returned byObject.keys() is the same as that provided by afor...in loop.
If you need the property values, useObject.values() instead. If you need both the property keys and values, useObject.entries() instead.
Examples
Using Object.keys()
// Basic arrayconst arr = ["a", "b", "c"];console.log(Object.keys(arr)); // ['0', '1', '2']// Array-like objectconst obj = { 0: "a", 1: "b", 2: "c" };console.log(Object.keys(obj)); // ['0', '1', '2']// Array-like object with random key orderingconst anObj = { 100: "a", 2: "b", 7: "c" };console.log(Object.keys(anObj)); // ['2', '7', '100']// getFoo is a non-enumerable propertyconst myObj = Object.create( {}, { getFoo: { value() { return this.foo; }, }, },);myObj.foo = 1;console.log(Object.keys(myObj)); // ['foo']If you wantall string-keyed own properties, including non-enumerable ones, seeObject.getOwnPropertyNames().
Using Object.keys() on primitives
Non-object arguments arecoerced to objects.undefined andnull cannot be coerced to objects and throw aTypeError upfront. Only strings may have own enumerable properties, while all other primitives return an empty array.
// Strings have indices as enumerable own propertiesconsole.log(Object.keys("foo")); // ['0', '1', '2']// Other primitives except undefined and null have no own propertiesconsole.log(Object.keys(100)); // []Note:In ES5, passing a non-object toObject.keys() threw aTypeError.
Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-object.keys |