128 lines
3.2 KiB
Markdown
128 lines
3.2 KiB
Markdown
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# is-data-descriptor [](https://www.npmjs.com/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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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm i is-data-descriptor --save
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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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## 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)
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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://www.npmjs.com/package/is-descriptor) | [homepage](https://github.com/jonschlinkert/is-descriptor)
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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)
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## Running tests
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Install dev dependencies:
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```sh
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$ npm i -d && npm test
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```
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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](https://github.com/jonschlinkert/is-data-descriptor/issues/new).
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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](http://twitter.com/jonschlinkert)
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## License
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Copyright © 2015 [Jon Schlinkert](https://github.com/jonschlinkert)
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Released under the MIT license.
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***
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_This file was generated by [verb](https://github.com/verbose/verb) on December 28, 2015._
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