| 1 | # is-extendable [](http://badge.fury.io/js/is-extendable)
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| 2 |
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| 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?"
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| 4 |
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| 5 | ## Install
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| 6 |
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| 7 | Install with [npm](https://www.npmjs.com/)
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| 8 |
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| 9 | ```sh
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| 10 | $ npm i is-extendable --save
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| 11 | ```
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| 12 |
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| 13 | ## Usage
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| 14 |
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| 15 | ```js
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| 16 | var isExtendable = require('is-extendable');
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| 17 | ```
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| 18 |
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| 19 | Returns true if the value is any of the following:
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| 20 |
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| 21 | * `array`
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| 22 | * `regexp`
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| 23 | * `plain object`
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| 24 | * `function`
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| 25 | * `date`
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| 26 | * `error`
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| 27 |
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| 28 | ## Notes
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| 29 |
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| 30 | All 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:
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| 31 |
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| 32 | * the value is not a primitive, or
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| 33 | * that the object is an `object`, `function`
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| 34 |
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| 35 | Also 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`.
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| 36 |
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| 37 | ## Related projects
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| 38 |
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| 39 | * [assign-deep](https://github.com/jonschlinkert/assign-deep): Deeply assign the enumerable properties of source objects to a destination object.
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| 40 | * [extend-shallow](https://github.com/jonschlinkert/extend-shallow): Extend an object with the properties of additional objects. node.js/javascript util.
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| 41 | * [isobject](https://github.com/jonschlinkert/isobject): Returns true if the value is an object and not an array or null.
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| 42 | * [is-plain-object](https://github.com/jonschlinkert/is-plain-object): Returns true if an object was created by the `Object` constructor.
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| 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.
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| 44 | * [kind-of](https://github.com/jonschlinkert/kind-of): Get the native type of a value.
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| 45 |
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| 46 | ## Running tests
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| 47 |
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| 48 | Install dev dependencies:
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| 49 |
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| 50 | ```sh
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| 51 | $ npm i -d && npm test
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| 52 | ```
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| 53 |
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| 54 | ## Contributing
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| 55 |
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| 56 | Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](https://github.com/jonschlinkert/is-extendable/issues/new)
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| 57 |
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| 58 | ## Author
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| 59 |
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| 60 | **Jon Schlinkert**
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| 61 |
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| 62 | + [github/jonschlinkert](https://github.com/jonschlinkert)
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| 63 | + [twitter/jonschlinkert](http://twitter.com/jonschlinkert)
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| 64 |
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| 65 | ## License
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| 66 |
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| 67 | Copyright © 2015 Jon Schlinkert
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| 68 | Released under the MIT license.
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| 69 |
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| 70 | ***
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| 71 |
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| 72 | _This file was generated by [verb-cli](https://github.com/assemble/verb-cli) on July 04, 2015._ |
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