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3.0.0 • Public • Published

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Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.


Install with npm:

$ npm install --save is-descriptor


const isDescriptor = require('is-descriptor');
isDescriptor({ value: 'foo' })
//=> true
isDescriptor({ get: function() {}, set: function() {} })
//=> true
isDescriptor({ get: 'foo', set: function() {} })
//=> false

You may also check for a descriptor by passing an object as the first argument and property name (string) as the second argument.

const obj = {};
obj.foo = null;
Object.defineProperty(obj, 'bar', { value: 'xyz' });
Reflect.defineProperty(obj, 'baz', { value: 'xyz' });
isDescriptor(obj, 'foo'); //=> true
isDescriptor(obj, 'bar'); //=> true
isDescriptor(obj, 'baz'); //=> true


value type

Returns false when not an object

isDescriptor('a'); //=> false
isDescriptor(null); //=> false
isDescriptor([]); //=> false

data descriptor

Returns true when the object has valid properties with valid values.

isDescriptor({ value: 'foo' }); //=> true
isDescriptor({ value: function() {} }); //=> true

Returns false when the object has invalid properties

isDescriptor({ value: 'foo', bar: 'baz' }); //=> false
isDescriptor({ value: 'foo', bar: 'baz' }); //=> false
isDescriptor({ value: 'foo', get: function() {} }); //=> false
isDescriptor({ get: function() {}, value: function() {} }); //=> false

false when a value is not the correct type

isDescriptor({ value: 'foo', enumerable: 'foo' }); //=> false
isDescriptor({ value: 'foo', configurable: 'foo' }); //=> false
isDescriptor({ value: 'foo', writable: 'foo' }); //=> false

accessor descriptor

true when the object has valid properties with valid values.

isDescriptor({ get: function() {}, set: function() {} }); //=> true
isDescriptor({ get: function() {} }); //=> true
isDescriptor({ set: function() {} }); //=> true

false when the object has invalid properties

isDescriptor({ get: function() {}, set: function() {}, bar: 'baz' }); //=> false
isDescriptor({ get: function() {}, writable: true }); //=> false
isDescriptor({ get: function() {}, value: true }); //=> false

Returns false when an accessor is not a function

isDescriptor({ get: function() {}, set: 'baz' }); //=> false
isDescriptor({ get: 'foo', set: function() {} }); //=> false
isDescriptor({ get: 'foo', bar: 'baz' }); //=> false
isDescriptor({ get: 'foo', set: 'baz' }); //=> false

Returns false when a value is not the correct type

isDescriptor({ get: function() {}, set: function() {}, enumerable: 'foo' }); //=> false
isDescriptor({ set: function() {}, configurable: 'foo' }); //=> false
isDescriptor({ get: function() {}, configurable: 'foo' }); //=> false



Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Running Tests

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:

$ npm install && npm test
Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

$ npm install -g verbose/verb#dev verb-generate-readme && verb

Related projects

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Jon Schlinkert


Copyright © 2018, Jon Schlinkert. Released under the MIT License.

This file was generated by verb-generate-readme, v0.8.0, on December 13, 2018.


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