| 1 | # is-extendable [](https://www.npmjs.com/package/is-extendable) [](https://npmjs.org/package/is-extendable) [](https://npmjs.org/package/is-extendable) [](https://travis-ci.org/jonschlinkert/is-extendable)
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| 2 |
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| 3 | > Returns true if a value is a plain object, array or function.
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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 install --save is-extendable
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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 | * plain object
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| 23 | * function
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| 24 |
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| 25 | ## Notes
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| 26 |
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| 27 | 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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| 28 |
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| 29 | * the value is not a primitive, or
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| 30 | * that the object is a plain object, function or array
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| 31 |
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| 32 | 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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| 33 |
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| 34 | ## Release history
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| 35 |
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| 36 | ### v1.0.0 - 2017/07/20
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| 37 |
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| 38 | **Breaking changes**
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| 39 |
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| 40 | * No longer considers date, regex or error objects to be extendable
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| 41 |
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| 42 | ## About
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| 43 |
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| 44 | ### Related projects
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| 45 |
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| 46 | * [assign-deep](https://www.npmjs.com/package/assign-deep): Deeply assign the enumerable properties and/or es6 Symbol properies of source objects to the target… [more](https://github.com/jonschlinkert/assign-deep) | [homepage](https://github.com/jonschlinkert/assign-deep "Deeply assign the enumerable properties and/or es6 Symbol properies of source objects to the target (first) object.")
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| 47 | * [is-equal-shallow](https://www.npmjs.com/package/is-equal-shallow): Does a shallow comparison of two objects, returning false if the keys or values differ. | [homepage](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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| 48 | * [is-plain-object](https://www.npmjs.com/package/is-plain-object): Returns true if an object was created by the `Object` constructor. | [homepage](https://github.com/jonschlinkert/is-plain-object "Returns true if an object was created by the `Object` constructor.")
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| 49 | * [isobject](https://www.npmjs.com/package/isobject): Returns true if the value is an object and not an array or null. | [homepage](https://github.com/jonschlinkert/isobject "Returns true if the value is an object and not an array or null.")
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| 50 | * [kind-of](https://www.npmjs.com/package/kind-of): Get the native type of a value. | [homepage](https://github.com/jonschlinkert/kind-of "Get the native type of a value.")
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| 51 |
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| 52 | ### Contributing
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| 53 |
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| 54 | Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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| 55 |
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| 56 | ### Building docs
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| 57 |
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| 58 | _(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
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| 59 |
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| 60 | To generate the readme, run the following command:
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| 61 |
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| 62 | ```sh
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| 63 | $ npm install -g verbose/verb#dev verb-generate-readme && verb
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| 64 | ```
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| 65 |
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| 66 | ### Running tests
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| 67 |
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| 68 | 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:
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| 69 |
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| 70 | ```sh
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| 71 | $ npm install && npm test
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| 72 | ```
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| 73 |
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| 74 | ### Author
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| 75 |
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| 76 | **Jon Schlinkert**
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| 77 |
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| 78 | * [github/jonschlinkert](https://github.com/jonschlinkert)
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| 79 | * [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
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| 80 |
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| 81 | ### License
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| 82 |
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| 83 | Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
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| 84 | Released under the [MIT License](LICENSE).
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| 85 |
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| 86 | ***
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| 87 |
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| 88 | _This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on July 20, 2017._ |
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