is-descriptor
Advanced tools
Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.
The is-descriptor npm package is used for checking if an object is a valid descriptor. Descriptors are objects that define the behavior of properties on JavaScript objects, such as whether they are writable, enumerable, or configurable, and they can also specify getter and setter functions. This package is useful for validation in libraries that manipulate object properties and descriptors, ensuring that operations like defining new properties or modifying existing ones are performed with valid descriptor objects.
Checking property descriptors
This feature allows you to check if a given object is a valid property descriptor. The code sample demonstrates checking various objects to see if they qualify as descriptors based on their properties.
const isDescriptor = require('is-descriptor');
console.log(isDescriptor({enumerable: false, configurable: true})); // true
console.log(isDescriptor({value: 'hello'})); // true
console.log(isDescriptor({get: function() {}})); // true
console.log(isDescriptor({set: undefined})); // falseThis package checks specifically for data descriptors, which are a type of property descriptor focusing on value properties rather than accessor properties (getters and setters). It's more specific compared to is-descriptor, which checks for both data and accessor descriptors.
Similar to is-data-descriptor, this package focuses on checking for accessor descriptors, which define getter and setter functions for a property. It complements is-data-descriptor by covering the other main type of property descriptor, offering a more focused approach compared to the broader checks performed by is-descriptor.
Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for fully completed data descriptors and accessor descriptors.
const isDescriptor = require('is-descriptor');
const assert = require('assert');
const defaults = { configurable: false, enumerable: false };
const dataDefaults = { ...defaults, writable: false};
assert.ok(isDescriptor({ ...dataDefaults, value: 'foo' }));
assert.ok(isDescriptor({ ...defaults, get() {}, set() {} }));
assert.ok(!isDescriptor({ ...defaults, get: 'foo', set() {} }));
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 = { foo: 'abc' };
Object.defineProperty(obj, 'bar', { value: 'xyz' });
Reflect.defineProperty(obj, 'baz', { value: 'xyz' });
assert.equal(isDescriptor(obj, 'foo'), true);
assert.equal(isDescriptor(obj, 'bar'), true);
assert.equal(isDescriptor(obj, 'baz'), true);
Returns false when not an object
assert.equal(isDescriptor('a'), false);
assert.equal(isDescriptor(null), false);
assert.equal(isDescriptor([]), false);
Returns true when the object has valid properties with valid values.
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo' }), true);
assert.equal(isDescriptor({ ...dataDefaults, value() {} }), true);
Returns false when the object has invalid properties
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', enumerable: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', configurable: 'baz' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', get() {} }), false);
assert.equal(isDescriptor({ ...dataDefaults, get() {}, value() {} }), false);
false when a value is not the correct type
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', enumerable: 'foo' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', configurable: 'foo' }), false);
assert.equal(isDescriptor({ ...dataDefaults, value: 'foo', writable: 'foo' }), false);
true when the object has valid properties with valid values.
assert.equal(isDescriptor({ ...defaults, get() {}, set() {} }), true);
assert.equal(isDescriptor({ ...defaults, get() {} }), true);
assert.equal(isDescriptor({ ...defaults, set() {} }), true);
false when the object has invalid properties
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, bar: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, enumerable: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, writable: true }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, value: true }), false);
Returns false when an accessor is not a function
assert.equal(isDescriptor({ ...defaults, get() {}, set: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', set() {} }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', bar: 'baz' }), false);
assert.equal(isDescriptor({ ...defaults, get: 'foo', set: 'baz' }), false);
Returns false when a value is not the correct type
assert.equal(isDescriptor({ ...defaults, get() {}, set() {}, enumerable: 'foo' }), false);
assert.equal(isDescriptor({ ...defaults, set() {}, configurable: 'foo' }), false);
assert.equal(isDescriptor({ ...defaults, get() {}, configurable: 'foo' }), false);
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Simply clone the repo, npm install, and run npm test
v3.1.1 - 2023-10-27
gopd and hasown d32fc37v0.1.7, v1.0.3`` [596c888`](https://github.com/inspect-js/is-descriptor/commit/596c888a558420697a396947cd24d0edd42e19ef)8bcf028544cdfe1130f793f8f09492ee1bf8da3a3cset and not get is still an accessor descriptor 269fb53files to exports 41b2d619fd1ac8@ljharb/eslint-config, aud, tape 52668c9is-accessor-descriptor, is-data-descriptor f4dbc735f4b0e191be7239eaa17cFAQs
Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.
The npm package is-descriptor receives a total of 25,124,620 weekly downloads. As such, is-descriptor popularity was classified as popular.
We found that is-descriptor demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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