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# is-descriptor [![NPM version](https://img.shields.io/npm/v/is-descriptor.svg?style=flat)](https://www.npmjs.com/package/is-descriptor) [![NPM monthly downloads](https://img.shields.io/npm/dm/is-descriptor.svg?style=flat)](https://npmjs.org/package/is-descriptor) [![NPM total downloads](https://img.shields.io/npm/dt/is-descriptor.svg?style=flat)](https://npmjs.org/package/is-descriptor) [![Linux Build Status](https://img.shields.io/travis/jonschlinkert/is-descriptor.svg?style=flat&label=Travis)](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._
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