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161 lines
5.2 KiB
Markdown
161 lines
5.2 KiB
Markdown
# is-data-descriptor [](https://www.npmjs.com/package/is-data-descriptor) [](https://npmjs.org/package/is-data-descriptor) [](https://npmjs.org/package/is-data-descriptor) [](https://travis-ci.org/jonschlinkert/is-data-descriptor)
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> Returns true if a value has the characteristics of a valid JavaScript data descriptor.
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Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support.
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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm install --save is-data-descriptor
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```
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## Usage
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```js
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var isDataDesc = require('is-data-descriptor');
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```
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## Examples
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`true` when the descriptor has valid properties with valid values.
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```js
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// `value` can be anything
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isDataDesc({value: 'foo'})
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isDataDesc({value: function() {}})
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isDataDesc({value: true})
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//=> true
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```
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`false` when not an object
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```js
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isDataDesc('a')
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//=> false
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isDataDesc(null)
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//=> false
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isDataDesc([])
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//=> false
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```
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`false` when the object has invalid properties
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```js
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isDataDesc({value: 'foo', bar: 'baz'})
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//=> false
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isDataDesc({value: 'foo', bar: 'baz'})
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//=> false
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isDataDesc({value: 'foo', get: function(){}})
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//=> false
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isDataDesc({get: function(){}, value: 'foo'})
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//=> false
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```
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`false` when a value is not the correct type
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```js
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isDataDesc({value: 'foo', enumerable: 'foo'})
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//=> false
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isDataDesc({value: 'foo', configurable: 'foo'})
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//=> false
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isDataDesc({value: 'foo', writable: 'foo'})
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//=> false
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```
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## Valid properties
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The only valid data descriptor properties are the following:
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* `configurable` (required)
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* `enumerable` (required)
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* `value` (optional)
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* `writable` (optional)
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To be a valid data descriptor, either `value` or `writable` must be defined.
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**Invalid properties**
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A descriptor may have additional _invalid_ properties (an error will **not** be thrown).
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```js
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var foo = {};
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Object.defineProperty(foo, 'bar', {
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enumerable: true,
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whatever: 'blah', // invalid, but doesn't cause an error
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get: function() {
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return 'baz';
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}
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});
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console.log(foo.bar);
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//=> 'baz'
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```
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## About
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<details>
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<summary><strong>Contributing</strong></summary>
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Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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</details>
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<details>
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<summary><strong>Running Tests</strong></summary>
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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:
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```sh
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$ npm install && npm test
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```
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</details>
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<details>
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<summary><strong>Building docs</strong></summary>
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_(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.)_
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To generate the readme, run the following command:
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```sh
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$ npm install -g verbose/verb#dev verb-generate-readme && verb
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```
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</details>
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### Related projects
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You might also be interested in these projects:
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* [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.")
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* [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.")
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* [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.")
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* [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.")
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### Contributors
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| **Commits** | **Contributor** |
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| --- | --- |
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| 21 | [jonschlinkert](https://github.com/jonschlinkert) |
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| 2 | [realityking](https://github.com/realityking) |
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### Author
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**Jon Schlinkert**
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* [github/jonschlinkert](https://github.com/jonschlinkert)
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* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
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### License
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Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
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Released under the [MIT License](LICENSE).
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***
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_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on November 01, 2017._ |