is-descriptor NPM version NPM monthly downloads NPM total downloads Linux Build Status

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

Install

Install with npm:

$ npm install --save is-descriptor

Usage

var 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.

var obj = {};
obj.foo = 'abc';

Object.defineProperty(obj, 'bar', {
  value: 'xyz'
});

isDescriptor(obj, 'foo');
//=> true
isDescriptor(obj, 'bar');
//=> true

Examples

value type

false when not an object

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

data descriptor

true when the object has valid properties with valid values.

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

false when the object has invalid properties

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

false when the object has invalid properties

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

false when an accessor is not a function

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

false when a value is not the correct type

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

About

Contributing

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

Contributors

Commits Contributor
24 jonschlinkert
1 doowb
1 wtgtybhertgeghgtwtg

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

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

Author

Jon Schlinkert

License

Copyright © 2017, Jon Schlinkert. Released under the MIT License.


This file was generated by verb-generate-readme, v0.6.0, on July 22, 2017.