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193 lines
5.7 KiB
193 lines
5.7 KiB
# 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) |
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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._ |