Divider

A simple utility to divide a string or string[] based on given indexes or delimiters.

🚀 Installation

You can install @nyaomaru/divider using your favorite package manager:

# Using pnpm (recommended)
pnpm install @nyaomaru/divider

# Using npm
npm install @nyaomaru/divider

# Using bun
bun add @nyaomaru/divider

# Using yarn
yarn add @nyaomaru/divider
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Deno / Bun (via JSR)

This package is also published on JSR and works in Deno and Bun without a bundler.

// Deno/Bun: import directly from JSR
import { divider } from 'jsr:@nyaomaru/divider';
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Version pinning examples:

// Pin a major version (recommended)
import { divider } from 'jsr:@nyaomaru/divider@^1';

// Or pin an exact version
import { divider } from 'jsr:@nyaomaru/divider@1.9.4';
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For Bun, you can also add it to your project manifest:

# Pin a major version in Bun
bun add jsr:@nyaomaru/divider@^1
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📖 Documentation

• 📝 Guide: https://divider-docs.vercel.app
• 🧪 API Reference: https://nyaomaru.github.io/divider/

📖 Usage

👉 Check out the full documentation here!

divider allows you to divide a string or an array of strings using index positions or delimiters.

📌 Basic Usage

import { divider } from '@nyaomaru/divider';

// Divide a string by index positions
const helloArray = divider('hello', 1, 3);
// ['h', 'el', 'lo']

const [hello1, hello2, ...restHello] = divider('hello', 1, 3, 4);
// hello1 = 'h'
// hello2 = 'el'
// restHello = ['l', 'o']

// Divide a string using a character separator
const divideWithString = divider('hello', 'e');
// ['h', 'llo']

const divideWithMultipleString = divider('hello', 'l');
// ['he', 'o']

// Divide an array of strings
const words = ['hello', 'world'];
const dividedWords = divider(words, 2);
// [['he', 'llo'], ['wo', 'rld']]
const dividedWordsWithFlattenOption = divider(words, 2, { flatten: true });
// ['he', 'llo', 'wo', 'rld']
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📌 Advanced Usage

// Mixed usage of indexes and characters
const complexDivide = divider('hello world', 3, 'o');
// ['hel', 'l', ' w', 'rld']

// Nested array handling
const nestedArray = divider(['hello', 'new world'], ' ', 2);
// [['he', 'llo'], ['ne', 'w wor', 'ld']]

// Flatten option to get a single array
const flatArray = divider(['hello', 'new world'], ' ', 2, { flatten: true });
// ['he', 'llo', 'ne', 'w', 'wor', 'ld']
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📌 dividerFirst() Usage

dividerFirst() returns only the first divided element from the result.

import { dividerFirst } from '@nyaomaru/divider';

const firstElement = dividerFirst('hello world', ' ');
// 'hello'

const firstArrayElement = dividerFirst(['hello', 'world'], 2);
// 'he'
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📌 dividerLast() Usage

dividerLast() returns only the last divided element from the result.

import { dividerLast } from '@nyaomaru/divider';

const lastElement = dividerLast('hello world', ' ');
// 'world'

const lastArrayElement = dividerLast(['hello', 'world'], 2);
// 'rld'
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📌 dividerLoop() Usage

import { dividerLoop } from '@nyaomaru/divider';

// Divide string into chunks of given size
const result = dividerLoop('abcdefghij', 3);
// ['abc', 'def', 'ghi', 'j']

// Supports flatten option for string[]
const result2 = dividerLoop(['hello', 'world'], 2, { flatten: true });
// ['he', 'll', 'ow', 'or', 'ld']

// You can also control where to start dividing using `startOffset`
const result3 = dividerLoop('abcdefghij', 3, { startOffset: 1 });
// ['abcd', 'efg', 'hij']

// Combine with flatten and trim
const result4 = dividerLoop(['  hello ', 'world  '], 2, {
  flatten: true,
  trim: true,
  startOffset: 1,
});
// ['h', 'el', 'lo', 'wor', 'ld']

// Limit the number of chunks using maxChunks
const result5 = dividerLoop('abcdefghij', 3, { maxChunks: 2 });
// ['abc', 'defghij']
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📌 dividerNumberString() Usage

import { dividerNumberString } from '@nyaomaru/divider';

// Divide numbers and letters from a string
const result = dividerNumberString('abc123def456');
// ['abc', '123', 'def', '456']

// Divide each string in a string[]
const result2 = dividerNumberString(['abc123', '45z']);
// [['abc', '123'], ['45', 'z']]

// Flatten option
const result3 = dividerNumberString(['abc123', '45z'], { flatten: true });
// ['abc', '123', '45', 'z']
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📌 Presets

Some common use cases are wrapped as presets for convenience.

Preset name	Description
emailDivider	Divide email into [local-part, domain] (by '@')
csvDivider	Divide comma-separated strings, with quoted field support
pathDivider	Divide file paths by / or |

Presets detail

🎯 General Options

Option	Type	Default	Description
flatten	boolean	false	If true, the resulting nested arrays are flattened into a single array.
trim	boolean	false	If true, trims whitespace from each divided segment.
preserveEmpty	boolean	false	If true, keeps empty segments produced by the split.
exclude	'none' / 'empty' / 'whitespace'	'none'	See detailed explanation below

flatten (default: false)

const words = ['hello', 'world'];
const result = divider(words, 2);
// [['he', 'llo'], ['wo', 'rld']]

const result = divider(words, 2, { flatten: true });
// ['he', 'llo', 'wo', 'rld']
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trim (default: false)

const result = divider('  hello world  ', 7, { trim: true });
// ['hello', 'world']

const result = divider(['  a  ', ' b  c '], ' ', {
  flatten: true,
  trim: true,
});
// ['a', 'b', 'c']
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preserveEmpty (default: false)

const defaultResult = divider('foo,,bar,', ',');
// ['foo', 'bar']

const preservedResult = divider('foo,,bar,', ',', { preserveEmpty: true });
// ['foo', '', 'bar', '']
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Keep placeholder blanks when they carry meaning (e.g., CSV cells, sparse logs, diff tooling). Combine with exclude to filter later in the pipeline.

exclude (default: 'none')

Option	Description
'none'	Do not exclude any segments (all results are kept).
'empty'	Exclude empty strings ('').
'whitespace'	Exclude strings that contain only whitespace characters (e.g., ' ').

Control how segments like empty strings ('') or whitespace-only strings (' ') are handled.

// Remove truly empty strings
const result = divider('a,,b', ',', { exclude: 'empty' });
// ['a', 'b']

// Remove both empty and whitespace-only strings
const result = divider('a, ,b', ',', { exclude: 'whitespace' });
// ['a', 'b']

// You can combine with `trim` for clearer results (note the trailing space)
const result = divider('a, ,b ', ',', {
  trim: true,
  exclude: 'whitespace',
});
// ['a', 'b']
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Special Options

Option	Type	Default	Description
startOffset	number	0	Starting index offset when dividing into chunks (only for dividerLoop)
maxChunks	number	∞	Maximum number of chunks allowed. Extra chunks are joined into the last chunk. (only for dividerLoop)

💡 Features

• 🧩 Flexible Division: Index-based and string-based separators
• 🧵 Handles Nested Input: Supports both string and string[]
• 🎛️ Optional Behaviors: flatten, trim, preserveEmpty, exclude
• 🎯 Targeted Extractors: dividerFirst(), dividerLast()
• 🔁 Loop Support: dividerLoop() for chunked division
• 🔢 Digit-Letter Splitter: dividerNumberString()

🛠 Contributing

We welcome contributions!

Please read our CONTRIBUTING.md guide before submitting a PR.

Thank you for your contribution. 😺

📚 Additional Documents

• DEVELOPER.md — Development setup and contributor guide
• CODE_OF_CONDUCT.md — Community standards and conduct
• CHANGELOG.md — Version history and notable changes

🟦 Deno / JSR Notes

• Import path alias @/ is supported in Deno via the included deno.json import map.
• Type-check locally with Deno: deno task check (or deno check ./src/index.ts).
• Publish to JSR from a tagged commit: deno publish.
• CI: On PRs, we run deno fmt --check / deno lint / deno check / deno test.
• CI JSR publish runs deno publish when a GitHub Release is published (OIDC-based; no personal token required).
• deno test is configured to only target tests-deno/** (Bun/Jest tests are excluded).
• For local development, Deno's unstable sloppy-imports is enabled to resolve the @/ alias (this does not affect JSR publishing or consumers).
• VSCode: to enable Bun type completions, add bun-types as a dev dependency and include "bun-types" in tests-bun/tsconfig.json types (this repo is preconfigured).
• VSCode: the Deno extension is enabled only for tests-deno/ (see .vscode/settings.json), which fixes typings for jsr:@std/assert.