# is-descriptor [](https://www.npmjs.com/package/is-descriptor) [](https://npmjs.org/package/is-descriptor) [](https://npmjs.org/package/is-descriptor) [](https://travis-ci.org/jonschlinkert/is-descriptor)
> Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.
## Install
Install with [npm](https://www.npmjs.com/):
```sh
$ npm install --save is-descriptor
```
## Usage
```js
var isDescriptor = require('is-descriptor');
isDescriptor({value: 'foo'})
//=> true
isDescriptor({get: function(){}, set: function(){}})
//=> true
isDescriptor({get: 'foo', set: function(){}})
//=> false
```
You may also check for a descriptor by passing an object as the first argument and property name (`string`) as the second argument.
```js
var obj = {};
obj.foo = 'abc';
Object.defineProperty(obj, 'bar', {
value: 'xyz'
});
isDescriptor(obj, 'foo');
//=> true
isDescriptor(obj, 'bar');
//=> true
```
## Examples
### value type
`false` when not an object
```js
isDescriptor('a');
//=> false
isDescriptor(null);
//=> false
isDescriptor([]);
//=> false
```
### data descriptor
`true` when the object has valid properties with valid values.
```js
isDescriptor({value: 'foo'});
//=> true
isDescriptor({value: noop});
//=> true
```
`false` when the object has invalid properties
```js
isDescriptor({value: 'foo', bar: 'baz'});
//=> false
isDescriptor({value: 'foo', bar: 'baz'});
//=> false
isDescriptor({value: 'foo', get: noop});
//=> false
isDescriptor({get: noop, value: noop});
//=> false
```
`false` when a value is not the correct type
```js
isDescriptor({value: 'foo', enumerable: 'foo'});
//=> false
isDescriptor({value: 'foo', configurable: 'foo'});
//=> false
isDescriptor({value: 'foo', writable: 'foo'});
//=> false
```
### accessor descriptor
`true` when the object has valid properties with valid values.
```js
isDescriptor({get: noop, set: noop});
//=> true
isDescriptor({get: noop});
//=> true
isDescriptor({set: noop});
//=> true
```
`false` when the object has invalid properties
```js
isDescriptor({get: noop, set: noop, bar: 'baz'});
//=> false
isDescriptor({get: noop, writable: true});
//=> false
isDescriptor({get: noop, value: true});
//=> false
```
`false` when an accessor is not a function
```js
isDescriptor({get: noop, set: 'baz'});
//=> false
isDescriptor({get: 'foo', set: noop});
//=> false
isDescriptor({get: 'foo', bar: 'baz'});
//=> false
isDescriptor({get: 'foo', set: 'baz'});
//=> false
```
`false` when a value is not the correct type
```js
isDescriptor({get: noop, set: noop, enumerable: 'foo'});
//=> false
isDescriptor({set: noop, configurable: 'foo'});
//=> false
isDescriptor({get: noop, configurable: 'foo'});
//=> false
```
## About
### Related 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. | [homepage](https://github.com/jonschlinkert/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. | [homepage](https://github.com/jonschlinkert/is-data-descriptor "Returns true if a value has the characteristics of a valid JavaScript data descriptor.")
* [is-descriptor](https://www.npmjs.com/package/is-descriptor): Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for… [more](https://github.com/jonschlinkert/is-descriptor) | [homepage](https://github.com/jonschlinkert/is-descriptor "Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.")
* [isobject](https://www.npmjs.com/package/isobject): Returns true if the value is an object and not an array or null. | [homepage](https://github.com/jonschlinkert/isobject "Returns true if the value is an object and not an array or null.")
### Contributing
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
### Contributors
| **Commits** | **Contributor** |
| --- | --- |
| 24 | [jonschlinkert](https://github.com/jonschlinkert) |
| 1 | [doowb](https://github.com/doowb) |
| 1 | [wtgtybhertgeghgtwtg](https://github.com/wtgtybhertgeghgtwtg) |
### Building docs
_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
To generate the readme, run the following command:
```sh
$ npm install -g verbose/verb#dev verb-generate-readme && verb
```
### Running tests
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
```sh
$ npm install && npm test
```
### Author
**Jon Schlinkert**
* [github/jonschlinkert](https://github.com/jonschlinkert)
* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
### License
Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
Released under the [MIT License](LICENSE).
***
_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on July 22, 2017._
Réz István