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187 lines
6.4 KiB
Markdown
187 lines
6.4 KiB
Markdown
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# is-number [](https://www.npmjs.com/package/is-number) [](https://npmjs.org/package/is-number) [](https://npmjs.org/package/is-number) [](https://travis-ci.org/jonschlinkert/is-number)
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> Returns true if the value is a finite number.
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Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support.
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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm install --save is-number
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```
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## Why is this needed?
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In JavaScript, it's not always as straightforward as it should be to reliably check if a value is a number. It's common for devs to use `+`, `-`, or `Number()` to cast a string value to a number (for example, when values are returned from user input, regex matches, parsers, etc). But there are many non-intuitive edge cases that yield unexpected results:
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```js
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console.log(+[]); //=> 0
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console.log(+''); //=> 0
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console.log(+' '); //=> 0
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console.log(typeof NaN); //=> 'number'
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```
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This library offers a performant way to smooth out edge cases like these.
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## Usage
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```js
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const isNumber = require('is-number');
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```
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See the [tests](./test.js) for more examples.
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### true
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```js
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isNumber(5e3); // true
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isNumber(0xff); // true
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isNumber(-1.1); // true
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isNumber(0); // true
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isNumber(1); // true
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isNumber(1.1); // true
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isNumber(10); // true
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isNumber(10.10); // true
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isNumber(100); // true
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isNumber('-1.1'); // true
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isNumber('0'); // true
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isNumber('012'); // true
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isNumber('0xff'); // true
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isNumber('1'); // true
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isNumber('1.1'); // true
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isNumber('10'); // true
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isNumber('10.10'); // true
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isNumber('100'); // true
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isNumber('5e3'); // true
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isNumber(parseInt('012')); // true
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isNumber(parseFloat('012')); // true
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```
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### False
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Everything else is false, as you would expect:
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```js
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isNumber(Infinity); // false
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isNumber(NaN); // false
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isNumber(null); // false
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isNumber(undefined); // false
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isNumber(''); // false
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isNumber(' '); // false
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isNumber('foo'); // false
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isNumber([1]); // false
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isNumber([]); // false
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isNumber(function () {}); // false
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isNumber({}); // false
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```
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## Release history
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### 7.0.0
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* Refactor. Now uses `.isFinite` if it exists.
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* Performance is about the same as v6.0 when the value is a string or number. But it's now 3x-4x faster when the value is not a string or number.
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### 6.0.0
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* Optimizations, thanks to @benaadams.
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### 5.0.0
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**Breaking changes**
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* removed support for `instanceof Number` and `instanceof String`
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## Benchmarks
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As with all benchmarks, take these with a grain of salt. See the [benchmarks](./benchmark/index.js) for more detail.
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```
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# all
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v7.0 x 413,222 ops/sec ±2.02% (86 runs sampled)
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v6.0 x 111,061 ops/sec ±1.29% (85 runs sampled)
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parseFloat x 317,596 ops/sec ±1.36% (86 runs sampled)
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fastest is 'v7.0'
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# string
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v7.0 x 3,054,496 ops/sec ±1.05% (89 runs sampled)
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v6.0 x 2,957,781 ops/sec ±0.98% (88 runs sampled)
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parseFloat x 3,071,060 ops/sec ±1.13% (88 runs sampled)
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fastest is 'parseFloat,v7.0'
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# number
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v7.0 x 3,146,895 ops/sec ±0.89% (89 runs sampled)
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v6.0 x 3,214,038 ops/sec ±1.07% (89 runs sampled)
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parseFloat x 3,077,588 ops/sec ±1.07% (87 runs sampled)
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fastest is 'v6.0'
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```
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## About
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<details>
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<summary><strong>Contributing</strong></summary>
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Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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</details>
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<details>
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<summary><strong>Running Tests</strong></summary>
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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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```sh
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$ npm install && npm test
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```
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</details>
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<details>
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<summary><strong>Building docs</strong></summary>
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_(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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To generate the readme, run the following command:
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```sh
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$ npm install -g verbose/verb#dev verb-generate-readme && verb
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```
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</details>
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### Related projects
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You might also be interested in these projects:
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* [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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* [is-primitive](https://www.npmjs.com/package/is-primitive): Returns `true` if the value is a primitive. | [homepage](https://github.com/jonschlinkert/is-primitive "Returns `true` if the value is a primitive. ")
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* [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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* [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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### Contributors
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| **Commits** | **Contributor** |
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| --- | --- |
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| 49 | [jonschlinkert](https://github.com/jonschlinkert) |
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| 5 | [charlike-old](https://github.com/charlike-old) |
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| 1 | [benaadams](https://github.com/benaadams) |
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| 1 | [realityking](https://github.com/realityking) |
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### Author
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**Jon Schlinkert**
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* [LinkedIn Profile](https://linkedin.com/in/jonschlinkert)
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* [GitHub Profile](https://github.com/jonschlinkert)
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* [Twitter Profile](https://twitter.com/jonschlinkert)
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### License
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Copyright © 2018, [Jon Schlinkert](https://github.com/jonschlinkert).
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Released under the [MIT License](LICENSE).
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***
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_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on June 15, 2018._
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