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._