@patrtorg/sunt-distinctio-illo

@patrtorg/sunt-distinctio-illo

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.

var isDataDesc = require('@patrtorg/sunt-distinctio-illo');
var assert = require('assert');

assert.equal(true, isDataDesc({ value: 'foo' }));
assert.equal(true, isDataDesc({ value: function () {} }));
assert.equal(true, isDataDesc({ value: true }));

assert.equal(false, isDataDesc('a'));
assert.equal(false, isDataDesc(null));
assert.equal(false, isDataDesc([]));

assert.equal(false, isDataDesc({ value: 'foo', bar: 'baz' }));
assert.equal(false, isDataDesc({ value: 'foo', bar: 'baz' }));
assert.equal(false, isDataDesc({ value: 'foo', get: function () {} }));
assert.equal(false, isDataDesc({ get: function () {}, value: 'foo' }) );
 
assert.equal(false, isDataDesc({ value: 'foo', enumerable: 'foo' }));
assert.equal(false, isDataDesc({ value: 'foo', configurable: 'foo' }));
assert.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).

var foo = {};

Object.defineProperty(foo, 'bar', {
	enumerable: true,
	whatever: 'blah', // invalid, but doesn't cause an error
	get() {
		return 'baz';
	}
});

assert.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