# is-descriptor

> Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.

Latest version **3.1.2** (published 2026-05-11) · MIT license · 0 weekly downloads

## Install

```sh
npm install is-descriptor
pnpm add is-descriptor
yarn add is-descriptor
bun add is-descriptor
```

## Health

**Score 50/100 (C)** — status: active.

Positive: esm support; no vulnerabilities.

Warnings: low downloads; no types.

## Facts

| | |
|---|---|
| Version | 3.1.2 |
| Published | 2026-05-11 |
| First published | 2015-08-31 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | ESM + CommonJS |
| Node | >= 0.4 |
| Dependencies | 4 |
| Unpacked size | 34.1 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 12 |
| Author | Jon Schlinkert |
| Maintainers | ljharb, jonschlinkert |
| Keywords | accessor, check, data, descriptor, get, getter, is, keys, object, properties, property, set, setter, type, valid, value |

## Links

- npm: https://www.npmjs.com/package/is-descriptor
- Repository: https://github.com/inspect-js/is-descriptor
- Issues: https://github.com/inspect-js/is-descriptor/issues
- npm.io page: https://npm.io/package/is-descriptor

## Dependencies (4)

- [gopd](https://npm.io/package/gopd.md) ^1.2.0
- [hasown](https://npm.io/package/hasown.md) ^2.0.3
- [is-data-descriptor](https://npm.io/package/is-data-descriptor.md) ^2.1.3
- [is-accessor-descriptor](https://npm.io/package/is-accessor-descriptor.md) ^3.0.5

## Alternatives

- [memory-cache](https://npm.io/package/memory-cache.md) — 795.0K weekly downloads
- [@httptoolkit/proxy-agent](https://npm.io/package/@httptoolkit/proxy-agent.md) — 11.2K weekly downloads
- [express-cache-controller](https://npm.io/package/express-cache-controller.md) — 5.3K weekly downloads
- [http-cache-middleware](https://npm.io/package/http-cache-middleware.md) — 4.5K weekly downloads
- [cache2](https://npm.io/package/cache2.md) — 1.5K weekly downloads

## Recent versions

- 3.1.2 (latest) — 2026-05-11
- 0.1.8 (v0-backport) — 2026-05-10
- 1.0.4 (v1-backport) — 2026-05-10
- 3.1.1 — 2023-10-28
- 0.1.7 — 2023-10-27
- 1.0.3 — 2023-10-27
- 3.1.0 — 2023-05-02
- 3.0.0 — 2018-12-14
- 1.0.2 — 2017-12-28
- 0.1.6 — 2017-07-22
- 1.0.1 — 2017-07-22
- 1.0.0 — 2017-02-25
- 0.1.5 — 2017-02-25
- 0.1.4 — 2015-12-28
- 0.1.3 — 2015-12-20
- … 3 more at https://npm.io/package/is-descriptor/versions

## README

# is-descriptor <sup>[![Version Badge][npm-version-svg]][package-url]</sup>

[![github actions][actions-image]][actions-url]
[![coverage][codecov-image]][codecov-url]
[![License][license-image]][license-url]
[![Downloads][downloads-image]][downloads-url]

[![npm badge][npm-badge-png]][package-url]

> Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for fully completed data descriptors and accessor descriptors.

## Usage

```js
const isDescriptor = require('is-descriptor');
const assert = require('assert');

const defaults = { configurable: false, enumerable: false };
const dataDefaults = { ...defaults, writable: false};

assert.ok(isDescriptor({ ...dataDefaults, value: 'foo' }));
assert.ok(isDescriptor({ ...defaults, get() {}, set() {} }));
assert.ok(!isDescriptor({ ...defaults, get: 'foo', set() {} }));
```

You may also check for a descriptor by passing an object as the first argument and property name (`string`) as the second argument.

```js
const obj = { foo: 'abc' };

Object.defineProperty(obj, 'bar', { value: 'xyz' });
Reflect.defineProperty(obj, 'baz', { value: 'xyz' });

assert.equal(isDescriptor(obj, 'foo'), true);
assert.equal(isDescriptor(obj, 'bar'), true);
assert.equal(isDescriptor(obj, 'baz'), true);
```

## Examples

### value type

Returns `false` when not an object

```js
assert.equal(isDescriptor('a'), false);
assert.equal(isDescriptor(null), false);
assert.equal(isDescriptor([]), false);
```

### data descriptor

Returns `true` when the object has valid properties with valid values.

```js
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo' }), true);
assert.equal(isDescriptor({ ...dataDefaults, value() {} }), true);
```

Returns `false` when the object has invalid properties

```js
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', enumerable: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', configurable: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', get() {} }), false);
assert.equal(isDescriptor({ ...dataDefaults, get() {}, value() {} }), false);
```

`false` when a value is not the correct type

```js
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', enumerable: 'foo' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', configurable: 'foo' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', writable: 'foo' }), false);
```

### accessor descriptor

`true` when the object has valid properties with valid values.

```js
assert.equal(isDescriptor({ ...defaults, get() {}, set() {} }), true);
assert.equal(isDescriptor({ ...defaults, get() {} }), true);
assert.equal(isDescriptor({ ...defaults, set() {} }), true);
```

`false` when the object has invalid properties

```js
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, bar: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, enumerable: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, writable: true }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, value: true }), false);
```

Returns `false` when an accessor is not a function

```js
assert.equal(isDescriptor({ ...defaults, get() {}, set: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', set() {} }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', set: 'baz' }), false);
```

Returns `false` when a value is not the correct type

```js
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, enumerable: 'foo' }), false);
assert.equal(isDescriptor({ ...defaults, set() {}, configurable: 'foo' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, configurable: 'foo' }), false);
```

### Related projects

You might also be interested in these projects:

* [is-accessor-descriptor](https://www.npmjs.com/package/is-accessor-descriptor): Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.
* [is-data-descriptor](https://www.npmjs.com/package/is-data-descriptor): Returns true if a value has the characteristics of a valid JavaScript data descriptor.
* [is-object](https://www.npmjs.com/package/is-object): Returns true if the value is an object and not an array or null.

## Tests
Simply clone the repo, `npm install`, and run `npm test`

[package-url]: https://npmjs.org/package/is-descriptor
[npm-version-svg]: https://versionbadg.es/inspect-js/is-descriptor.svg
[deps-svg]: https://david-dm.org/inspect-js/is-descriptor.svg
[deps-url]: https://david-dm.org/inspect-js/is-descriptor
[dev-deps-svg]: https://david-dm.org/inspect-js/is-descriptor/dev-status.svg
[dev-deps-url]: https://david-dm.org/inspect-js/is-descriptor#info=devDependencies
[npm-badge-png]: https://nodei.co/npm/is-descriptor.png?downloads=true&stars=true
[license-image]: https://img.shields.io/npm/l/is-descriptor.svg
[license-url]: LICENSE
[downloads-image]: https://img.shields.io/npm/dm/is-descriptor.svg
[downloads-url]: https://npm-stat.com/charts.html?package=is-descriptor
[codecov-image]: https://codecov.io/gh/inspect-js/is-descriptor/branch/main/graphs/badge.svg
[codecov-url]: https://app.codecov.io/gh/inspect-js/is-descriptor/
[actions-image]: https://img.shields.io/github/check-runs/inspect-js/is-descriptor/main
[actions-url]: https://github.com/inspect-js/is-descriptor/actions

---
_Source: https://npm.io/package/is-descriptor · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._