is-data-descriptor

Returns true if a value has the characteristics of a valid JavaScript data descriptor.

Examples

true when the descriptor has valid properties with valid values. false when not an object or when the object has invalid properties.

1var isDataDesc = require('is-data-descriptor');
2var assert = require('assert');
3
4assert.equal(true, isDataDesc({ value: 'foo' }));
5assert.equal(true, isDataDesc({ value: function () {} }));
6assert.equal(true, isDataDesc({ value: true }));
7
8assert.equal(false, isDataDesc('a'));
9assert.equal(false, isDataDesc(null));
10assert.equal(false, isDataDesc([]));
11
12assert.equal(false, isDataDesc({ value: 'foo', bar: 'baz' }));
13assert.equal(false, isDataDesc({ value: 'foo', bar: 'baz' }));
14assert.equal(false, isDataDesc({ value: 'foo', get: function () {} }));
15assert.equal(false, isDataDesc({ get: function () {}, value: 'foo' }) );
16 
17assert.equal(false, isDataDesc({ value: 'foo', enumerable: 'foo' }));
18assert.equal(false, isDataDesc({ value: 'foo', configurable: 'foo' }));
19assert.equal(false, isDataDesc({ value: 'foo', writable: 'foo' }));

Valid properties

The only valid data descriptor properties are the following:

• configurable (required)
• enumerable (required)
• value (optional)
• writable (optional)

To be a valid data descriptor, either value or writable must be defined.

Invalid properties

A descriptor may have additional invalid properties (an error will not be thrown).

1var foo = {};
2
3Object.defineProperty(foo, 'bar', {
4	enumerable: true,
5	whatever: 'blah', // invalid, but doesn't cause an error
6	get() {
7		return 'baz';
8	}
9});
10
11assert.equal(foo.bar, 'baz');

Related projects

• is-accessor-descriptor: Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.
• is-descriptor: Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for… more

Tests

Simply clone the repo, npm install, and run npm test