193 lines
5.7 KiB
Markdown
193 lines
5.7 KiB
Markdown
# 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)
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> Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.
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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-descriptor
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```
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## Usage
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```js
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var isDescriptor = require('is-descriptor');
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isDescriptor({value: 'foo'})
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//=> true
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isDescriptor({get: function(){}, set: function(){}})
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//=> true
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isDescriptor({get: 'foo', set: function(){}})
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//=> false
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```
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You may also check for a descriptor by passing an object as the first argument and property name (`string`) as the second argument.
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```js
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var obj = {};
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obj.foo = 'abc';
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Object.defineProperty(obj, 'bar', {
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value: 'xyz'
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});
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isDescriptor(obj, 'foo');
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//=> true
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isDescriptor(obj, 'bar');
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//=> true
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```
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## Examples
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### value type
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`false` when not an object
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```js
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isDescriptor('a');
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//=> false
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isDescriptor(null);
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//=> false
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isDescriptor([]);
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//=> false
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```
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### data descriptor
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`true` when the object has valid properties with valid values.
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```js
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isDescriptor({value: 'foo'});
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//=> true
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isDescriptor({value: noop});
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//=> true
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```
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`false` when the object has invalid properties
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```js
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isDescriptor({value: 'foo', bar: 'baz'});
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//=> false
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isDescriptor({value: 'foo', bar: 'baz'});
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//=> false
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isDescriptor({value: 'foo', get: noop});
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//=> false
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isDescriptor({get: noop, value: noop});
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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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isDescriptor({value: 'foo', enumerable: 'foo'});
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//=> false
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isDescriptor({value: 'foo', configurable: 'foo'});
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//=> false
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isDescriptor({value: 'foo', writable: 'foo'});
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//=> false
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```
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### accessor descriptor
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`true` when the object has valid properties with valid values.
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```js
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isDescriptor({get: noop, set: noop});
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//=> true
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isDescriptor({get: noop});
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//=> true
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isDescriptor({set: noop});
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//=> true
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```
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`false` when the object has invalid properties
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```js
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isDescriptor({get: noop, set: noop, bar: 'baz'});
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//=> false
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isDescriptor({get: noop, writable: true});
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//=> false
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isDescriptor({get: noop, value: true});
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//=> false
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```
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`false` when an accessor is not a function
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```js
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isDescriptor({get: noop, set: 'baz'});
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//=> false
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isDescriptor({get: 'foo', set: noop});
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//=> false
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isDescriptor({get: 'foo', bar: 'baz'});
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//=> false
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isDescriptor({get: 'foo', set: 'baz'});
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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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isDescriptor({get: noop, set: noop, enumerable: 'foo'});
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//=> false
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isDescriptor({set: noop, configurable: 'foo'});
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//=> false
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isDescriptor({get: noop, configurable: 'foo'});
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//=> false
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```
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## About
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### Related 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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### Contributing
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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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### Contributors
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| **Commits** | **Contributor** |
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| --- | --- |
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| 24 | [jonschlinkert](https://github.com/jonschlinkert) |
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| 1 | [doowb](https://github.com/doowb) |
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| 1 | [wtgtybhertgeghgtwtg](https://github.com/wtgtybhertgeghgtwtg) |
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### Building docs
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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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### Running tests
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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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### 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 July 22, 2017._ |