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  1. # is-number [![NPM version](https://badge.fury.io/js/is-number.svg)](http://badge.fury.io/js/is-number) [![Build Status](https://travis-ci.org/jonschlinkert/is-number.svg)](https://travis-ci.org/jonschlinkert/is-number)
  2. > Returns true if the value is a number. comprehensive tests.
  3. To understand some of the rationale behind the decisions made in this library (and to learn about some oddities of number evaluation in JavaScript), [see this gist](https://gist.github.com/jonschlinkert/e30c70c713da325d0e81).
  4. ## Install
  5. Install with [npm](https://www.npmjs.com/)
  6. ```sh
  7. $ npm i is-number --save
  8. ```
  9. ## Usage
  10. ```js
  11. var isNumber = require('is-number');
  12. ```
  13. ### true
  14. See the [tests](./test.js) for more examples.
  15. ```js
  16. isNumber(5e3) //=> 'true'
  17. isNumber(0xff) //=> 'true'
  18. isNumber(-1.1) //=> 'true'
  19. isNumber(0) //=> 'true'
  20. isNumber(1) //=> 'true'
  21. isNumber(1.1) //=> 'true'
  22. isNumber(10) //=> 'true'
  23. isNumber(10.10) //=> 'true'
  24. isNumber(100) //=> 'true'
  25. isNumber('-1.1') //=> 'true'
  26. isNumber('0') //=> 'true'
  27. isNumber('012') //=> 'true'
  28. isNumber('0xff') //=> 'true'
  29. isNumber('1') //=> 'true'
  30. isNumber('1.1') //=> 'true'
  31. isNumber('10') //=> 'true'
  32. isNumber('10.10') //=> 'true'
  33. isNumber('100') //=> 'true'
  34. isNumber('5e3') //=> 'true'
  35. isNumber(parseInt('012')) //=> 'true'
  36. isNumber(parseFloat('012')) //=> 'true'
  37. ```
  38. ### False
  39. See the [tests](./test.js) for more examples.
  40. ```js
  41. isNumber('foo') //=> 'false'
  42. isNumber([1]) //=> 'false'
  43. isNumber([]) //=> 'false'
  44. isNumber(function () {}) //=> 'false'
  45. isNumber(Infinity) //=> 'false'
  46. isNumber(NaN) //=> 'false'
  47. isNumber(new Array('abc')) //=> 'false'
  48. isNumber(new Array(2)) //=> 'false'
  49. isNumber(new Buffer('abc')) //=> 'false'
  50. isNumber(null) //=> 'false'
  51. isNumber(undefined) //=> 'false'
  52. isNumber({abc: 'abc'}) //=> 'false'
  53. ```
  54. ## Other projects
  55. * [even](https://www.npmjs.com/package/even): Get the even numbered items from an array. | [homepage](https://github.com/jonschlinkert/even)
  56. * [is-even](https://www.npmjs.com/package/is-even): Return true if the given number is even. | [homepage](https://github.com/jonschlinkert/is-even)
  57. * [is-odd](https://www.npmjs.com/package/is-odd): Returns true if the given number is odd. | [homepage](https://github.com/jonschlinkert/is-odd)
  58. * [is-primitive](https://www.npmjs.com/package/is-primitive): Returns `true` if the value is a primitive. | [homepage](https://github.com/jonschlinkert/is-primitive)
  59. * [kind-of](https://www.npmjs.com/package/kind-of): Get the native type of a value. | [homepage](https://github.com/jonschlinkert/kind-of)
  60. * [odd](https://www.npmjs.com/package/odd): Get the odd numbered items from an array. | [homepage](https://github.com/jonschlinkert/odd)
  61. ## Contributing
  62. Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](https://github.com/jonschlinkert/is-number/issues/new).
  63. ## Run tests
  64. Install dev dependencies:
  65. ```sh
  66. $ npm i -d && npm test
  67. ```
  68. ## Author
  69. **Jon Schlinkert**
  70. + [github/jonschlinkert](https://github.com/jonschlinkert)
  71. + [twitter/jonschlinkert](http://twitter.com/jonschlinkert)
  72. ## License
  73. Copyright © 2015 Jon Schlinkert
  74. Released under the MIT license.
  75. ***
  76. _This file was generated by [verb-cli](https://github.com/assemble/verb-cli) on November 22, 2015._