# fill-range [![Donate](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=W8YFZ425KND68) [![NPM version](https://img.shields.io/npm/v/fill-range.svg?style=flat)](https://www.npmjs.com/package/fill-range) [![NPM monthly downloads](https://img.shields.io/npm/dm/fill-range.svg?style=flat)](https://npmjs.org/package/fill-range) [![NPM total downloads](https://img.shields.io/npm/dt/fill-range.svg?style=flat)](https://npmjs.org/package/fill-range) [![Linux Build Status](https://img.shields.io/travis/jonschlinkert/fill-range.svg?style=flat&label=Travis)](https://travis-ci.org/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` Please consider following this project's author, [Jon Schlinkert](https://github.com/jonschlinkert), and consider starring the project to show your :heart: and support. ## Install Install with [npm](https://www.npmjs.com/): ```sh $ npm install --save fill-range ``` ## Usage Expands numbers and letters, optionally using a `step` as the last argument. _(Numbers may be defined as JavaScript numbers or strings)_. ```js const fill = require('fill-range'); // fill(from, to[, step, options]); console.log(fill('1', '10')); //=> ['1', '2', '3', '4', '5', '6', '7', '8', '9', '10'] console.log(fill('1', '10', { toRegex: true })); //=> [1-9]|10 ``` **Params** * `from`: **{String|Number}** the number or letter to start with * `to`: **{String|Number}** the number or letter to end with * `step`: **{String|Number|Object|Function}** Optionally pass a [step](#optionsstep) to use. * `options`: **{Object|Function}**: See all available [options](#options) ## Examples By default, an array of values is returned. **Alphabetical ranges** ```js console.log(fill('a', 'e')); //=> ['a', 'b', 'c', 'd', 'e'] console.log(fill('A', 'E')); //=> [ 'A', 'B', 'C', 'D', 'E' ] ``` **Numerical ranges** Numbers can be defined as actual numbers or strings. ```js console.log(fill(1, 5)); //=> [ 1, 2, 3, 4, 5 ] console.log(fill('1', '5')); //=> [ 1, 2, 3, 4, 5 ] ``` **Negative ranges** Numbers can be defined as actual numbers or strings. ```js console.log(fill('-5', '-1')); //=> [ '-5', '-4', '-3', '-2', '-1' ] console.log(fill('-5', '5')); //=> [ '-5', '-4', '-3', '-2', '-1', '0', '1', '2', '3', '4', '5' ] ``` **Steps (increments)** ```js // numerical ranges with increments console.log(fill('0', '25', 4)); //=> [ '0', '4', '8', '12', '16', '20', '24' ] console.log(fill('0', '25', 5)); //=> [ '0', '5', '10', '15', '20', '25' ] console.log(fill('0', '25', 6)); //=> [ '0', '6', '12', '18', '24' ] // alphabetical ranges with increments console.log(fill('a', 'z', 4)); //=> [ 'a', 'e', 'i', 'm', 'q', 'u', 'y' ] console.log(fill('a', 'z', 5)); //=> [ 'a', 'f', 'k', 'p', 'u', 'z' ] console.log(fill('a', 'z', 6)); //=> [ 'a', 'g', 'm', 's', 'y' ] ``` ## Options ### options.step **Type**: `number` (formatted as a string or number) **Default**: `undefined` **Description**: The increment to use for the range. Can be used with letters or numbers. **Example(s)** ```js // numbers console.log(fill('1', '10', 2)); //=> [ '1', '3', '5', '7', '9' ] console.log(fill('1', '10', 3)); //=> [ '1', '4', '7', '10' ] console.log(fill('1', '10', 4)); //=> [ '1', '5', '9' ] // letters console.log(fill('a', 'z', 5)); //=> [ 'a', 'f', 'k', 'p', 'u', 'z' ] console.log(fill('a', 'z', 7)); //=> [ 'a', 'h', 'o', 'v' ] console.log(fill('a', 'z', 9)); //=> [ 'a', 'j', 's' ] ``` ### options.strictRanges **Type**: `boolean` **Default**: `false` **Description**: By default, `null` is returned when an invalid range is passed. Enable this option to throw a `RangeError` on invalid ranges. **Example(s)** The following are all invalid: ```js fill('1.1', '2'); // decimals not supported in ranges fill('a', '2'); // incompatible range values fill(1, 10, 'foo'); // invalid "step" argument ``` ### options.stringify **Type**: `boolean` **Default**: `undefined` **Description**: Cast all returned values to strings. By default, integers are returned as numbers. **Example(s)** ```js console.log(fill(1, 5)); //=> [ 1, 2, 3, 4, 5 ] console.log(fill(1, 5, { stringify: true })); //=> [ '1', '2', '3', '4', '5' ] ``` ### options.toRegex **Type**: `boolean` **Default**: `undefined` **Description**: Create a regex-compatible source string, instead of expanding values to an array. **Example(s)** ```js // alphabetical range console.log(fill('a', 'e', { toRegex: true })); //=> '[a-e]' // alphabetical with step console.log(fill('a', 'z', 3, { toRegex: true })); //=> 'a|d|g|j|m|p|s|v|y' // numerical range console.log(fill('1', '100', { toRegex: true })); //=> '[1-9]|[1-9][0-9]|100' // numerical range with zero padding console.log(fill('000001', '100000', { toRegex: true })); //=> '0{5}[1-9]|0{4}[1-9][0-9]|0{3}[1-9][0-9]{2}|0{2}[1-9][0-9]{3}|0[1-9][0-9]{4}|100000' ``` ### options.transform **Type**: `function` **Default**: `undefined` **Description**: Customize each value in the returned array (or [string](#optionstoRegex)). _(you can also pass this function as the last argument to `fill()`)_. **Example(s)** ```js // add zero padding console.log(fill(1, 5, value => String(value).padStart(4, '0'))); //=> ['0001', '0002', '0003', '0004', '0005'] ``` ## About

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).

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: ```sh $ npm install && npm test ```

Building docs

_(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.)_ To generate the readme, run the following command: ```sh $ npm install -g verbose/verb#dev verb-generate-readme && verb ```

### Contributors | **Commits** | **Contributor** | | --- | --- | | 116 | [jonschlinkert](https://github.com/jonschlinkert) | | 4 | [paulmillr](https://github.com/paulmillr) | | 2 | [realityking](https://github.com/realityking) | | 2 | [bluelovers](https://github.com/bluelovers) | | 1 | [edorivai](https://github.com/edorivai) | | 1 | [wtgtybhertgeghgtwtg](https://github.com/wtgtybhertgeghgtwtg) | ### Author **Jon Schlinkert** * [GitHub Profile](https://github.com/jonschlinkert) * [Twitter Profile](https://twitter.com/jonschlinkert) * [LinkedIn Profile](https://linkedin.com/in/jonschlinkert) Please consider supporting me on Patreon, or [start your own Patreon page](https://patreon.com/invite/bxpbvm)!

### License Copyright © 2019, [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), v0.8.0, on April 08, 2019._

c	File Name	Size	T	Date
-	LICENSE	1091	%	2026-05-20 11:21:42
-	README.md	7486	md	2026-05-20 11:21:42
-	index.js	6406	js	2026-05-20 11:21:42
-	package.json	1760	json	2026-05-20 11:21:42

🌲 / quartz node_modules fill-range

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