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    to-regex-range
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    5.0.1 • Public • Published

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    Pass two numbers, get a regex-compatible source string for matching ranges. Validated against more than 2.78 million test assertions.

    Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.

    Install

    Install with npm:

    $ npm install --save to-regex-range
    What does this do?

    This libary generates the source string to be passed to new RegExp() for matching a range of numbers.

    Example

    const toRegexRange = require('to-regex-range');
    const regex = new RegExp(toRegexRange('15', '95'));

    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).


    Why use this library?

    Convenience

    Creating regular expressions for matching numbers gets deceptively complicated pretty fast.

    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:

    • regex for matching 1 => /1/ (easy enough)
    • regex for matching 1 through 5 => /[1-5]/ (not bad...)
    • regex for matching 1 or 5 => /(1|5)/ (still easy...)
    • regex for matching 1 through 50 => /([1-9]|[1-4][0-9]|50)/ (uh-oh...)
    • regex for matching 1 through 55 => /([1-9]|[1-4][0-9]|5[0-5])/ (no prob, I can do this...)
    • 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...)
    • 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!)

    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.

    Learn more

    If you're interested in learning more about character classes and other regex features, I personally have always found regular-expressions.info to be pretty useful.

    Heavily tested

    As of April 07, 2019, this library runs >1m test assertions against generated regex-ranges to provide brute-force verification that results are correct.

    Tests run in ~280ms on my MacBook Pro, 2.5 GHz Intel Core i7.

    Optimized

    Generated regular expressions are optimized:

    • duplicate sequences and character classes are reduced using quantifiers
    • smart enough to use ? conditionals when number(s) or range(s) can be positive or negative
    • uses fragment caching to avoid processing the same exact string more than once

    Usage

    Add this library to your javascript application with the following line of code

    const toRegexRange = require('to-regex-range');

    The main export is a function that takes two integers: the min value and max value (formatted as strings or numbers).

    const source = toRegexRange('15', '95');
    //=> 1[5-9]|[2-8][0-9]|9[0-5]
     
    const regex = new RegExp(`^${source}$`);
    console.log(regex.test('14')); //=> false
    console.log(regex.test('50')); //=> true
    console.log(regex.test('94')); //=> true
    console.log(regex.test('96')); //=> false

    Options

    options.capture

    Type: boolean

    Deafault: undefined

    Wrap the returned value in parentheses when there is more than one regex condition. Useful when you're dynamically generating ranges.

    console.log(toRegexRange('-10', '10'));
    //=> -[1-9]|-?10|[0-9]
     
    console.log(toRegexRange('-10', '10', { capture: true }));
    //=> (-[1-9]|-?10|[0-9])

    options.shorthand

    Type: boolean

    Deafault: undefined

    Use the regex shorthand for [0-9]:

    console.log(toRegexRange('0', '999999'));
    //=> [0-9]|[1-9][0-9]{1,5}
     
    console.log(toRegexRange('0', '999999', { shorthand: true }));
    //=> \d|[1-9]\d{1,5}

    options.relaxZeros

    Type: boolean

    Default: true

    This option relaxes matching for leading zeros when when ranges are zero-padded.

    const source = toRegexRange('-0010', '0010');
    const regex = new RegExp(`^${source}$`);
    console.log(regex.test('-10')); //=> true
    console.log(regex.test('-010')); //=> true
    console.log(regex.test('-0010')); //=> true
    console.log(regex.test('10')); //=> true
    console.log(regex.test('010')); //=> true
    console.log(regex.test('0010')); //=> true

    When relaxZeros is false, matching is strict:

    const source = toRegexRange('-0010', '0010', { relaxZeros: false });
    const regex = new RegExp(`^${source}$`);
    console.log(regex.test('-10')); //=> false
    console.log(regex.test('-010')); //=> false
    console.log(regex.test('-0010')); //=> true
    console.log(regex.test('10')); //=> false
    console.log(regex.test('010')); //=> false
    console.log(regex.test('0010')); //=> true

    Examples

    Range Result Compile time
    toRegexRange(-10, 10) -[1-9]\|-?10\|[0-9] 132μs
    toRegexRange(-100, -10) -1[0-9]\|-[2-9][0-9]\|-100 50μs
    toRegexRange(-100, 100) -[1-9]\|-?[1-9][0-9]\|-?100\|[0-9] 42μs
    toRegexRange(001, 100) 0{0,2}[1-9]\|0?[1-9][0-9]\|100 109μs
    toRegexRange(001, 555) 0{0,2}[1-9]\|0?[1-9][0-9]\|[1-4][0-9]{2}\|5[0-4][0-9]\|55[0-5] 51μs
    toRegexRange(0010, 1000) 0{0,2}1[0-9]\|0{0,2}[2-9][0-9]\|0?[1-9][0-9]{2}\|1000 31μs
    toRegexRange(1, 50) [1-9]\|[1-4][0-9]\|50 24μs
    toRegexRange(1, 55) [1-9]\|[1-4][0-9]\|5[0-5] 23μs
    toRegexRange(1, 555) [1-9]\|[1-9][0-9]\|[1-4][0-9]{2}\|5[0-4][0-9]\|55[0-5] 30μs
    toRegexRange(1, 5555) [1-9]\|[1-9][0-9]{1,2}\|[1-4][0-9]{3}\|5[0-4][0-9]{2}\|55[0-4][0-9]\|555[0-5] 43μs
    toRegexRange(111, 555) 11[1-9]\|1[2-9][0-9]\|[2-4][0-9]{2}\|5[0-4][0-9]\|55[0-5] 38μs
    toRegexRange(29, 51) 29\|[34][0-9]\|5[01] 24μs
    toRegexRange(31, 877) 3[1-9]\|[4-9][0-9]\|[1-7][0-9]{2}\|8[0-6][0-9]\|87[0-7] 32μs
    toRegexRange(5, 5) 5 8μs
    toRegexRange(5, 6) 5\|6 11μs
    toRegexRange(1, 2) 1\|2 6μs
    toRegexRange(1, 5) [1-5] 15μs
    toRegexRange(1, 10) [1-9]\|10 22μs
    toRegexRange(1, 100) [1-9]\|[1-9][0-9]\|100 25μs
    toRegexRange(1, 1000) [1-9]\|[1-9][0-9]{1,2}\|1000 31μs
    toRegexRange(1, 10000) [1-9]\|[1-9][0-9]{1,3}\|10000 34μs
    toRegexRange(1, 100000) [1-9]\|[1-9][0-9]{1,4}\|100000 36μs
    toRegexRange(1, 1000000) [1-9]\|[1-9][0-9]{1,5}\|1000000 42μs
    toRegexRange(1, 10000000) [1-9]\|[1-9][0-9]{1,6}\|10000000 42μs

    Heads up!

    Order of arguments

    When the min is larger than the max, values will be flipped to create a valid range:

    toRegexRange('51', '29');

    Is effectively flipped to:

    toRegexRange('29', '51');
    //=> 29|[3-4][0-9]|5[0-1]

    Steps / increments

    This library does not support steps (increments). A pr to add support would be welcome.

    History

    v2.0.0 - 2017-04-21

    New features

    Adds support for zero-padding!

    v1.0.0

    Optimizations

    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.

    Attribution

    Inspired by the python library range-regex.

    About

    Contributing

    Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

    Running Tests

    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:

    $ npm install && npm test
    Building docs

    (This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

    To generate the readme, run the following command:

    $ npm install -g verbose/verb#dev verb-generate-readme && verb

    Related projects

    You might also be interested in these projects:

    • expand-range: Fast, bash-like range expansion. Expand a range of numbers or letters, uppercase or lowercase. Used… more | homepage
    • fill-range: Fill in a range of numbers or letters, optionally passing an increment or step to… more | homepage
    • micromatch: Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch. | homepage
    • repeat-element: Create an array by repeating the given value n times. | homepage
    • repeat-string: Repeat the given string n times. Fastest implementation for repeating a string. | homepage

    Contributors

    Commits Contributor
    63 jonschlinkert
    3 doowb
    2 realityking

    Author

    Jon Schlinkert

    Please consider supporting me on Patreon, or start your own Patreon page!

    License

    Copyright © 2019, Jon Schlinkert. Released under the MIT License.


    This file was generated by verb-generate-readme, v0.8.0, on April 07, 2019.

    Install

    npm i to-regex-range

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    Version

    5.0.1

    License

    MIT

    Unpacked Size

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    Collaborators

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