113 lines
3.6 KiB
Markdown
113 lines
3.6 KiB
Markdown
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# is-data-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 data descriptor.
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## Install
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Install with [npm](https://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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var assert = require('assert');
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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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assert.equal(isDataDesc({ value: 'foo' }), true);
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assert.equal(isDataDesc({ value: function () {} }), true);
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assert.equal(isDataDesc({ value: true }), true);
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```
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`false` when not an object
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```js
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assert.equal(isDataDesc('a'), false);
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assert.equal(isDataDesc(null), 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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assert.equal(isDataDesc({ value: 'foo', enumerable: 'baz' }), false);
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assert.equal(isDataDesc({ value: 'foo', configurable: 'baz' }), false);
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assert.equal(isDataDesc({ value: 'foo', get() {} }), false);
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assert.equal(isDataDesc({ get() {}, value: 'foo' }), 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(isDataDesc({ value: 'foo', enumerable: 'foo' }), false);
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assert.equal(isDataDesc({ value: 'foo', configurable: 'foo' }), false);
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assert.equal(isDataDesc({ value: 'foo', writable: 'foo' }), 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() {
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return 'baz';
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}
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});
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assert.equal(foo.bar, 'baz');
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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://npmjs.com/is-accessor-descriptor): Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.
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* [is-descriptor](https://npmjs.com/is-descriptor): Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for… [more](https://npmjs.com/is-descriptor)
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[package-url]: https://npmjs.org/package/is-data-descriptor
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[npm-version-svg]: https://versionbadg.es/inspect-js/is-data-descriptor.svg
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[deps-svg]: https://david-dm.org/inspect-js/is-data-descriptor.svg
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[deps-url]: https://david-dm.org/inspect-js/is-data-descriptor
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[dev-deps-svg]: https://david-dm.org/inspect-js/is-data-descriptor/dev-status.svg
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[dev-deps-url]: https://david-dm.org/inspect-js/is-data-descriptor#info=devDependencies
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[npm-badge-png]: https://nodei.co/npm/is-data-descriptor.png?downloads=true&stars=true
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[license-image]: https://img.shields.io/npm/l/is-data-descriptor.svg
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[license-url]: LICENSE
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[downloads-image]: https://img.shields.io/npm/dm/is-data-descriptor.svg
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[downloads-url]: https://npm-stat.com/charts.html?package=is-data-descriptor
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[codecov-image]: https://codecov.io/gh/inspect-js/is-data-descriptor/branch/main/graphs/badge.svg
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[codecov-url]: https://app.codecov.io/gh/inspect-js/is-data-descriptor/
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[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/inspect-js/is-data-descriptor
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[actions-url]: https://github.com/inspect-js/is-data-descriptor/actions
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