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  1. # to-regex-range [![NPM version](https://img.shields.io/npm/v/to-regex-range.svg?style=flat)](https://www.npmjs.com/package/to-regex-range) [![NPM monthly downloads](https://img.shields.io/npm/dm/to-regex-range.svg?style=flat)](https://npmjs.org/package/to-regex-range) [![NPM total downloads](https://img.shields.io/npm/dt/to-regex-range.svg?style=flat)](https://npmjs.org/package/to-regex-range) [![Linux Build Status](https://img.shields.io/travis/micromatch/to-regex-range.svg?style=flat&label=Travis)](https://travis-ci.org/micromatch/to-regex-range)
  2. > Pass two numbers, get a regex-compatible source string for matching ranges. Validated against more than 2.78 million test assertions.
  3. ## Install
  4. Install with [npm](https://www.npmjs.com/):
  5. ```sh
  6. $ npm install --save to-regex-range
  7. ```
  8. Install with [yarn](https://yarnpkg.com):
  9. ```sh
  10. $ yarn add to-regex-range
  11. ```
  12. <details>
  13. <summary><strong>What does this do?</strong></summary>
  14. <br>
  15. This libary generates the `source` string to be passed to `new RegExp()` for matching a range of numbers.
  16. **Example**
  17. ```js
  18. var toRegexRange = require('to-regex-range');
  19. var regex = new RegExp(toRegexRange('15', '95'));
  20. ```
  21. A string is returned so that you can do whatever you need with it before passing it to `new RegExp()` (like adding `^` or `$` boundaries, defining flags, or combining it another string).
  22. <br>
  23. </details>
  24. <details>
  25. <summary><strong>Why use this library?</strong></summary>
  26. <br>
  27. ### Convenience
  28. Creating regular expressions for matching numbers gets deceptively complicated pretty fast.
  29. For example, let's say you need a validation regex for matching part of a user-id, postal code, social security number, tax id, etc:
  30. * regex for matching `1` => `/1/` (easy enough)
  31. * regex for matching `1` through `5` => `/[1-5]/` (not bad...)
  32. * regex for matching `1` or `5` => `/(1|5)/` (still easy...)
  33. * regex for matching `1` through `50` => `/([1-9]|[1-4][0-9]|50)/` (uh-oh...)
  34. * regex for matching `1` through `55` => `/([1-9]|[1-4][0-9]|5[0-5])/` (no prob, I can do this...)
  35. * regex for matching `1` through `555` => `/([1-9]|[1-9][0-9]|[1-4][0-9]{2}|5[0-4][0-9]|55[0-5])/` (maybe not...)
  36. * regex for matching `0001` through `5555` => `/(0{3}[1-9]|0{2}[1-9][0-9]|0[1-9][0-9]{2}|[1-4][0-9]{3}|5[0-4][0-9]{2}|55[0-4][0-9]|555[0-5])/` (okay, I get the point!)
  37. The numbers are contrived, but they're also really basic. In the real world you might need to generate a regex on-the-fly for validation.
  38. **Learn more**
  39. If you're interested in learning more about [character classes](http://www.regular-expressions.info/charclass.html) and other regex features, I personally have always found [regular-expressions.info](http://www.regular-expressions.info/charclass.html) to be pretty useful.
  40. ### Heavily tested
  41. As of April 27, 2017, this library runs [2,783,483 test assertions](./test/test.js) against generated regex-ranges to provide brute-force verification that results are indeed correct.
  42. Tests run in ~870ms on my MacBook Pro, 2.5 GHz Intel Core i7.
  43. ### Highly optimized
  44. Generated regular expressions are highly optimized:
  45. * duplicate sequences and character classes are reduced using quantifiers
  46. * smart enough to use `?` conditionals when number(s) or range(s) can be positive or negative
  47. * uses fragment caching to avoid processing the same exact string more than once
  48. <br>
  49. </details>
  50. ## Usage
  51. Add this library to your javascript application with the following line of code
  52. ```js
  53. var toRegexRange = require('to-regex-range');
  54. ```
  55. The main export is a function that takes two integers: the `min` value and `max` value (formatted as strings or numbers).
  56. ```js
  57. var source = toRegexRange('15', '95');
  58. //=> 1[5-9]|[2-8][0-9]|9[0-5]
  59. var re = new RegExp('^' + source + '$');
  60. console.log(re.test('14')); //=> false
  61. console.log(re.test('50')); //=> true
  62. console.log(re.test('94')); //=> true
  63. console.log(re.test('96')); //=> false
  64. ```
  65. ## Options
  66. ### options.capture
  67. **Type**: `boolean`
  68. **Deafault**: `undefined`
  69. Wrap the returned value in parentheses when there is more than one regex condition. Useful when you're dynamically generating ranges.
  70. ```js
  71. console.log(toRegexRange('-10', '10'));
  72. //=> -[1-9]|-?10|[0-9]
  73. console.log(toRegexRange('-10', '10', {capture: true}));
  74. //=> (-[1-9]|-?10|[0-9])
  75. ```
  76. ### options.shorthand
  77. **Type**: `boolean`
  78. **Deafault**: `undefined`
  79. Use the regex shorthand for `[0-9]`:
  80. ```js
  81. console.log(toRegexRange('0', '999999'));
  82. //=> [0-9]|[1-9][0-9]{1,5}
  83. console.log(toRegexRange('0', '999999', {shorthand: true}));
  84. //=> \d|[1-9]\d{1,5}
  85. ```
  86. ### options.relaxZeros
  87. **Type**: `boolean`
  88. **Default**: `true`
  89. This option only applies to **negative zero-padded ranges**. By default, when a negative zero-padded range is defined, the number of leading zeros is relaxed using `-0*`.
  90. ```js
  91. console.log(toRegexRange('-001', '100'));
  92. //=> -0*1|0{2}[0-9]|0[1-9][0-9]|100
  93. console.log(toRegexRange('-001', '100', {relaxZeros: false}));
  94. //=> -0{2}1|0{2}[0-9]|0[1-9][0-9]|100
  95. ```
  96. <details>
  97. <summary><strong>Why are zeros relaxed for negative zero-padded ranges by default?</strong></summary>
  98. Consider the following.
  99. ```js
  100. var regex = toRegexRange('-001', '100');
  101. ```
  102. _Note that `-001` and `100` are both three digits long_.
  103. In most zero-padding implementations, only a single leading zero is enough to indicate that zero-padding should be applied. Thus, the leading zeros would be "corrected" on the negative range in the example to `-01`, instead of `-001`, to make total length of each string no greater than the length of the largest number in the range (in other words, `-001` is 4 digits, but `100` is only three digits).
  104. If zeros were not relaxed by default, you might expect the resulting regex of the above pattern to match `-001` - given that it's defined that way in the arguments - _but it wouldn't_. It would, however, match `-01`. This gets even more ambiguous with large ranges, like `-01` to `1000000`.
  105. Thus, we relax zeros by default to provide a more predictable experience for users.
  106. </details>
  107. ## Examples
  108. | **Range** | **Result** | **Compile time** |
  109. | --- | --- | --- |
  110. | `toRegexRange('5, 5')` | `5` | _33μs_ |
  111. | `toRegexRange('5, 6')` | `5\|6` | _53μs_ |
  112. | `toRegexRange('29, 51')` | `29\|[34][0-9]\|5[01]` | _699μs_ |
  113. | `toRegexRange('31, 877')` | `3[1-9]\|[4-9][0-9]\|[1-7][0-9]{2}\|8[0-6][0-9]\|87[0-7]` | _711μs_ |
  114. | `toRegexRange('111, 555')` | `11[1-9]\|1[2-9][0-9]\|[2-4][0-9]{2}\|5[0-4][0-9]\|55[0-5]` | _62μs_ |
  115. | `toRegexRange('-10, 10')` | `-[1-9]\|-?10\|[0-9]` | _74μs_ |
  116. | `toRegexRange('-100, -10')` | `-1[0-9]\|-[2-9][0-9]\|-100` | _49μs_ |
  117. | `toRegexRange('-100, 100')` | `-[1-9]\|-?[1-9][0-9]\|-?100\|[0-9]` | _45μs_ |
  118. | `toRegexRange('001, 100')` | `0{2}[1-9]\|0[1-9][0-9]\|100` | _158μs_ |
  119. | `toRegexRange('0010, 1000')` | `0{2}1[0-9]\|0{2}[2-9][0-9]\|0[1-9][0-9]{2}\|1000` | _61μs_ |
  120. | `toRegexRange('1, 2')` | `1\|2` | _10μs_ |
  121. | `toRegexRange('1, 5')` | `[1-5]` | _24μs_ |
  122. | `toRegexRange('1, 10')` | `[1-9]\|10` | _23μs_ |
  123. | `toRegexRange('1, 100')` | `[1-9]\|[1-9][0-9]\|100` | _30μs_ |
  124. | `toRegexRange('1, 1000')` | `[1-9]\|[1-9][0-9]{1,2}\|1000` | _52μs_ |
  125. | `toRegexRange('1, 10000')` | `[1-9]\|[1-9][0-9]{1,3}\|10000` | _47μs_ |
  126. | `toRegexRange('1, 100000')` | `[1-9]\|[1-9][0-9]{1,4}\|100000` | _44μs_ |
  127. | `toRegexRange('1, 1000000')` | `[1-9]\|[1-9][0-9]{1,5}\|1000000` | _49μs_ |
  128. | `toRegexRange('1, 10000000')` | `[1-9]\|[1-9][0-9]{1,6}\|10000000` | _63μs_ |
  129. ## Heads up!
  130. **Order of arguments**
  131. When the `min` is larger than the `max`, values will be flipped to create a valid range:
  132. ```js
  133. toRegexRange('51', '29');
  134. ```
  135. Is effectively flipped to:
  136. ```js
  137. toRegexRange('29', '51');
  138. //=> 29|[3-4][0-9]|5[0-1]
  139. ```
  140. **Steps / increments**
  141. This library does not support steps (increments). A pr to add support would be welcome.
  142. ## History
  143. ### v2.0.0 - 2017-04-21
  144. **New features**
  145. Adds support for zero-padding!
  146. ### v1.0.0
  147. **Optimizations**
  148. Repeating ranges are now grouped using quantifiers. rocessing time is roughly the same, but the generated regex is much smaller, which should result in faster matching.
  149. ## Attribution
  150. Inspired by the python library [range-regex](https://github.com/dimka665/range-regex).
  151. ## About
  152. ### Related projects
  153. * [expand-range](https://www.npmjs.com/package/expand-range): Fast, bash-like range expansion. Expand a range of numbers or letters, uppercase or lowercase. See… [more](https://github.com/jonschlinkert/expand-range) | [homepage](https://github.com/jonschlinkert/expand-range "Fast, bash-like range expansion. Expand a range of numbers or letters, uppercase or lowercase. See the benchmarks. Used by micromatch.")
  154. * [fill-range](https://www.npmjs.com/package/fill-range): Fill in a range of numbers or letters, optionally passing an increment or `step` to… [more](https://github.com/jonschlinkert/fill-range) | [homepage](https://github.com/jonschlinkert/fill-range "Fill in a range of numbers or letters, optionally passing an increment or `step` to use, or create a regex-compatible range with `options.toRegex`")
  155. * [micromatch](https://www.npmjs.com/package/micromatch): Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch. | [homepage](https://github.com/jonschlinkert/micromatch "Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch.")
  156. * [repeat-element](https://www.npmjs.com/package/repeat-element): Create an array by repeating the given value n times. | [homepage](https://github.com/jonschlinkert/repeat-element "Create an array by repeating the given value n times.")
  157. * [repeat-string](https://www.npmjs.com/package/repeat-string): Repeat the given string n times. Fastest implementation for repeating a string. | [homepage](https://github.com/jonschlinkert/repeat-string "Repeat the given string n times. Fastest implementation for repeating a string.")
  158. ### Contributing
  159. Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
  160. ### Building docs
  161. _(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.)_
  162. To generate the readme, run the following command:
  163. ```sh
  164. $ npm install -g verbose/verb#dev verb-generate-readme && verb
  165. ```
  166. ### Running tests
  167. 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:
  168. ```sh
  169. $ npm install && npm test
  170. ```
  171. ### Author
  172. **Jon Schlinkert**
  173. * [github/jonschlinkert](https://github.com/jonschlinkert)
  174. * [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
  175. ### License
  176. Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
  177. Released under the [MIT License](LICENSE).
  178. ***
  179. _This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on April 27, 2017._