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# is-data-descriptor [![NPM version](https://img.shields.io/npm/v/is-data-descriptor.svg?style=flat)](https://www.npmjs.com/package/is-data-descriptor) [![NPM monthly downloads](https://img.shields.io/npm/dm/is-data-descriptor.svg?style=flat)](https://npmjs.org/package/is-data-descriptor) [![NPM total downloads](https://img.shields.io/npm/dt/is-data-descriptor.svg?style=flat)](https://npmjs.org/package/is-data-descriptor) [![Linux Build Status](https://img.shields.io/travis/jonschlinkert/is-data-descriptor.svg?style=flat&label=Travis)](https://travis-ci.org/jonschlinkert/is-data-descriptor)
> Returns true if a value has the characteristics of a valid JavaScript data descriptor.
Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support.
## Install
Install with [npm](https://www.npmjs.com/):
```sh $ npm install --save is-data-descriptor ```
## Usage
```js var isDataDesc = require('is-data-descriptor'); ```
## Examples
`true` when the descriptor has valid properties with valid values.
```js // `value` can be anything isDataDesc({value: 'foo'}) isDataDesc({value: function() {}}) isDataDesc({value: true}) //=> true ```
`false` when not an object
```js isDataDesc('a') //=> false isDataDesc(null) //=> false isDataDesc([]) //=> false ```
`false` when the object has invalid properties
```js isDataDesc({value: 'foo', bar: 'baz'}) //=> false isDataDesc({value: 'foo', bar: 'baz'}) //=> false isDataDesc({value: 'foo', get: function(){}}) //=> false isDataDesc({get: function(){}, value: 'foo'}) //=> false ```
`false` when a value is not the correct type
```js isDataDesc({value: 'foo', enumerable: 'foo'}) //=> false isDataDesc({value: 'foo', configurable: 'foo'}) //=> false isDataDesc({value: 'foo', writable: 'foo'}) //=> false ```
## Valid properties
The only valid data descriptor properties are the following:
* `configurable` (required) * `enumerable` (required) * `value` (optional) * `writable` (optional)
To be a valid data descriptor, either `value` or `writable` must be defined.
**Invalid properties**
A descriptor may have additional _invalid_ properties (an error will **not** be thrown).
```js var foo = {};
Object.defineProperty(foo, 'bar', { enumerable: true, whatever: 'blah', // invalid, but doesn't cause an error get: function() { return 'baz'; } });
console.log(foo.bar); //=> 'baz' ```
## About
<details> <summary><strong>Contributing</strong></summary>
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
</details>
<details> <summary><strong>Running Tests</strong></summary>
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 ```
</details>
<details> <summary><strong>Building docs</strong></summary>
_(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 ```
</details>
### 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. | [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.")
### Contributors
| **Commits** | **Contributor** | | --- | --- | | 21 | [jonschlinkert](https://github.com/jonschlinkert) | | 2 | [realityking](https://github.com/realityking) |
### 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 November 01, 2017._
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