1# is-extendable [![NPM version](https://badge.fury.io/js/is-extendable.svg)](http://badge.fury.io/js/is-extendable)
2
3> Returns true if a value is any of the object types: array, regexp, plain object, function or date. This is useful for determining if a value can be extended, e.g. "can the value have keys?"
4
5## Install
6
7Install with [npm](https://www.npmjs.com/)
8
9```sh
10$ npm i is-extendable --save
11```
12
13## Usage
14
15```js
16var isExtendable = require('is-extendable');
17```
18
19Returns true if the value is any of the following:
20
21* `array`
22* `regexp`
23* `plain object`
24* `function`
25* `date`
26* `error`
27
28## Notes
29
30All objects in JavaScript can have keys, but it's a pain to check for this, since we ether need to verify that the value is not `null` or `undefined` and:
31
32* the value is not a primitive, or
33* that the object is an `object`, `function`
34
35Also note that an `extendable` object is not the same as an [extensible object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isExtensible), which is one that (in es6) is not sealed, frozen, or marked as non-extensible using `preventExtensions`.
36
37## Related projects
38
39* [assign-deep](https://github.com/jonschlinkert/assign-deep): Deeply assign the enumerable properties of source objects to a destination object.
40* [extend-shallow](https://github.com/jonschlinkert/extend-shallow): Extend an object with the properties of additional objects. node.js/javascript util.
41* [isobject](https://github.com/jonschlinkert/isobject): Returns true if the value is an object and not an array or null.
42* [is-plain-object](https://github.com/jonschlinkert/is-plain-object): Returns true if an object was created by the `Object` constructor.
43* [is-equal-shallow](https://github.com/jonschlinkert/is-equal-shallow): Does a shallow comparison of two objects, returning false if the keys or values differ.
44* [kind-of](https://github.com/jonschlinkert/kind-of): Get the native type of a value.
45
46## Running tests
47
48Install dev dependencies:
49
50```sh
51$ npm i -d && npm test
52```
53
54## Contributing
55
56Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](https://github.com/jonschlinkert/is-extendable/issues/new)
57
58## Author
59
60**Jon Schlinkert**
61
62+ [github/jonschlinkert](https://github.com/jonschlinkert)
63+ [twitter/jonschlinkert](http://twitter.com/jonschlinkert)
64
65## License
66
67Copyright © 2015 Jon Schlinkert
68Released under the MIT license.
69
70***
71
72_This file was generated by [verb-cli](https://github.com/assemble/verb-cli) on July 04, 2015._