135 lines
4.7 KiB
Markdown
135 lines
4.7 KiB
Markdown
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# is-descriptor <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
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[![github actions][actions-image]][actions-url]
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[![coverage][codecov-image]][codecov-url]
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[![License][license-image]][license-url]
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[![Downloads][downloads-image]][downloads-url]
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[![npm badge][npm-badge-png]][package-url]
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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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## Usage
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```js
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const isDescriptor = require('is-descriptor');
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const assert = require('assert');
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assert.equal(isDescriptor({ value: 'foo' }), true);
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assert.equal(isDescriptor({ get() {}, set() {} }), true);
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assert.equal(isDescriptor({ get: 'foo', set() {} }), 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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const 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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assert.equal(isDescriptor(obj, 'foo'), true);
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assert.equal(isDescriptor(obj, 'bar'), 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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assert.equal(isDescriptor('a'), false);
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assert.equal(isDescriptor(null), false);
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assert.equal(isDescriptor([]), 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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assert.equal(isDescriptor({ value: 'foo' }), true);
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assert.equal(isDescriptor({ value() {} }), 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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assert.equal(isDescriptor({ value: 'foo', enumerable: 'baz' }), false);
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assert.equal(isDescriptor({ value: 'foo', configurable: 'baz' }), false);
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assert.equal(isDescriptor({ value: 'foo', get() {} }), false);
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assert.equal(isDescriptor({ get() {}, value() {} }), 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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assert.equal(isDescriptor({ value: 'foo', enumerable: 'foo' }), false);
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assert.equal(isDescriptor({ value: 'foo', configurable: 'foo' }), false);
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assert.equal(isDescriptor({ value: 'foo', writable: 'foo' }), 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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assert.equal(isDescriptor({ get() {}, set() {} }), true);
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assert.equal(isDescriptor({ get() {} }), true);
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assert.equal(isDescriptor({ set() {} }), 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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assert.equal(isDescriptor({ get() {}, set() {}, enumerable: 'baz' }), false);
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assert.equal(isDescriptor({ get() {}, writable: true }), false);
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assert.equal(isDescriptor({ get() {}, value: true }), 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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assert.equal(isDescriptor({ get() {}, set: 'baz' }), false);
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assert.equal(isDescriptor({ get: 'foo', set() {} }), false);
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assert.equal(isDescriptor({ get: 'foo', bar: 'baz' }), false);
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assert.equal(isDescriptor({ get: 'foo', set: 'baz' }), 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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assert.equal(isDescriptor({ get() {}, set() {}, enumerable: 'foo' }), false);
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assert.equal(isDescriptor({ set() {}, configurable: 'foo' }), false);
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assert.equal(isDescriptor({ get() {}, configurable: 'foo' }), false);
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```
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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.
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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.
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* [is-object](https://www.npmjs.com/package/is-object): Returns true if the value is an object and not an array or null.
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## Tests
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Simply clone the repo, `npm install`, and run `npm test`
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[package-url]: https://npmjs.org/package/is-descriptor
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[npm-version-svg]: https://versionbadg.es/inspect-js/is-descriptor.svg
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[deps-svg]: https://david-dm.org/inspect-js/is-descriptor.svg
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[deps-url]: https://david-dm.org/inspect-js/is-descriptor
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[dev-deps-svg]: https://david-dm.org/inspect-js/is-descriptor/dev-status.svg
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[dev-deps-url]: https://david-dm.org/inspect-js/is-descriptor#info=devDependencies
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[npm-badge-png]: https://nodei.co/npm/is-descriptor.png?downloads=true&stars=true
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[license-image]: https://img.shields.io/npm/l/is-descriptor.svg
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[license-url]: LICENSE
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[downloads-image]: https://img.shields.io/npm/dm/is-descriptor.svg
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[downloads-url]: https://npm-stat.com/charts.html?package=is-descriptor
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[codecov-image]: https://codecov.io/gh/inspect-js/is-descriptor/branch/main/graphs/badge.svg
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[codecov-url]: https://app.codecov.io/gh/inspect-js/is-descriptor/
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[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/inspect-js/is-descriptor
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[actions-url]: https://github.com/inspect-js/is-descriptor/actions
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