| # posix-character-classes [](https://www.npmjs.com/package/posix-character-classes) [](https://npmjs.org/package/posix-character-classes) [](https://npmjs.org/package/posix-character-classes) [](https://travis-ci.org/jonschlinkert/posix-character-classes) |
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| > POSIX character classes for creating regular expressions. |
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| ## Install |
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| Install with [npm](https://www.npmjs.com/): |
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| ```sh |
| $ npm install --save posix-character-classes |
| ``` |
| |
| Install with [yarn](https://yarnpkg.com): |
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| ```sh |
| $ yarn add posix-character-classes |
| ``` |
| |
| ## Usage |
| |
| ```js |
| var posix = require('posix-character-classes'); |
| console.log(posix.alpha); |
| //=> 'A-Za-z' |
| ``` |
| |
| ## POSIX Character classes |
| |
| The POSIX standard supports the following classes or categories of charactersh (note that classes must be defined within brackets)<sup class="footnote-ref"><a href="#fn1" id="fnref1">[1]</a></sup>: |
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| | **POSIX class** | **Equivalent to** | **Matches** | |
| | --- | --- | --- | |
| | `[:alnum:]` | `[A-Za-z0-9]` | digits, uppercase and lowercase letters | |
| | `[:alpha:]` | `[A-Za-z]` | upper- and lowercase letters | |
| | `[:ascii:]` | `[\x00-\x7F]` | ASCII characters | |
| | `[:blank:]` | `[ \t]` | space and TAB characters only | |
| | `[:cntrl:]` | `[\x00-\x1F\x7F]` | Control characters | |
| | `[:digit:]` | `[0-9]` | digits | |
| | `[:graph:]` | `[^[:cntrl:]]` | graphic characters (all characters which have graphic representation) | |
| | `[:lower:]` | `[a-z]` | lowercase letters | |
| | `[:print:]` | `[[:graph] ]` | graphic characters and space | |
| | `[:punct:]` | ``[-!"#$%&'()*+,./:;<=>?@[]^_`{ | }~]`` | all punctuation characters (all graphic characters except letters and digits) | |
| | `[:space:]` | `[ \t\n\r\f\v]` | all blank (whitespace) characters, including spaces, tabs, new lines, carriage returns, form feeds, and vertical tabs | |
| | `[:upper:]` | `[A-Z]` | uppercase letters | |
| | `[:word:]` | `[A-Za-z0-9_]` | word characters | |
| | `[:xdigit:]` | `[0-9A-Fa-f]` | hexadecimal digits | |
| |
| ## Examples |
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| * `a[[:digit:]]b` matches `a0b`, `a1b`, ..., `a9b`. |
| * `a[:digit:]b` is invalid, character classes must be enclosed in brackets |
| * `[[:digit:]abc]` matches any digit, as well as `a`, `b`, and `c`. |
| * `[abc[:digit:]]` is the same as the previous, matching any digit, as well as `a`, `b`, and `c` |
| * `[^ABZ[:lower:]]` matches any character except lowercase letters, `A`, `B`, and `Z`. |
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| ## About |
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| ### Contributing |
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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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| ### Building docs |
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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 |
| $ npm install -g verbose/verb#dev verb-generate-readme && verb |
| ``` |
| |
| ### Running tests |
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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: |
| |
| ```sh |
| $ npm install && npm test |
| ``` |
| |
| ### Author |
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| **Jon Schlinkert** |
| |
| * [github/jonschlinkert](https://github.com/jonschlinkert) |
| * [twitter/jonschlinkert](https://twitter.com/jonschlinkert) |
| |
| ### License |
| |
| Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert). |
| Released under the [MIT License](LICENSE). |
| |
| *** |
| |
| _This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.5.0, on April 20, 2017._ |
| |
| <hr class="footnotes-sep"> |
| <section class="footnotes"> |
| <ol class="footnotes-list"> |
| <li id="fn1" class="footnote-item">table and examples are based on the WikiBooks page for [Regular Expressions/POSIX Basic Regular Expressions](https://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Basic_Regular_Expressions), which is available under the [Creative Commons Attribution-ShareAlike License](https://creativecommons.org/licenses/by-sa/3.0/). <a href="#fnref1" class="footnote-backref">↩</a> |
| |
| </li> |
| </ol> |
| </section> |
