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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 :heart: and support.

Install

Install with npm:

$ npm install --save to-regex-range
<details> <summary><strong>What does this do?</strong></summary> <br>

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).

<br> </details> <details> <summary><strong>Why use this library?</strong></summary> <br>

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:

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:

<br> </details>

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

RangeResultCompile time
toRegexRange(-10, 10)-[1-9]|-?10|[0-9]132μs
toRegexRange(-100, -10)-1[0-9]|-[2-9][0-9]|-10050μs
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]|100109μs
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}|100031μs
toRegexRange(1, 50)[1-9]|[1-4][0-9]|5024μs
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)58μs
toRegexRange(5, 6)5|611μs
toRegexRange(1, 2)1|26μs
toRegexRange(1, 5)[1-5]15μs
toRegexRange(1, 10)[1-9]|1022μs
toRegexRange(1, 100)[1-9]|[1-9][0-9]|10025μs
toRegexRange(1, 1000)[1-9]|[1-9][0-9]{1,2}|100031μs
toRegexRange(1, 10000)[1-9]|[1-9][0-9]{1,3}|1000034μs
toRegexRange(1, 100000)[1-9]|[1-9][0-9]{1,4}|10000036μs
toRegexRange(1, 1000000)[1-9]|[1-9][0-9]{1,5}|100000042μs
toRegexRange(1, 10000000)[1-9]|[1-9][0-9]{1,6}|1000000042μs

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

<details> <summary><strong>Contributing</strong></summary>

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

</details> <details> <summary><strong>Running Tests</strong></summary>

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
</details> <details> <summary><strong>Building docs</strong></summary>

(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
</details>

Related projects

You might also be interested in these projects:

Contributors

CommitsContributor
63jonschlinkert
3doowb
2realityking

Author

Jon Schlinkert

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

<a href="https://www.patreon.com/jonschlinkert"> <img src="https://c5.patreon.com/external/logo/become_a_patron_button@2x.png" height="50"> </a>

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.