dmatch

dmatch - Elegant Pattern Matching for JS/TS

Introducing dmatch, an elegant and tiny utility library designed for intuitive pattern matching in JavaScript and TypeScript.

Below 2KB for the core functionality without compression. 0 runtime dependencies

Table of Contents

• dmatch - Elegant Pattern Matching for JS/TS
  • Table of Contents
  • Installation
    • npm:
  • Usage
    • On-the-Fly Matching
    • Reusable Matching
  • Advanced Use Cases
    • Dynamic Pricing
    • Custom Logic
  • Behaviors and Edge Cases
    • No Match and No Default
  • License

Installation

npm:

npm install dmatch

Usage

dmatch is versatile, allowing you to either match patterns on-the-fly or preconfigure matchers for reusable scenarios.

On-the-Fly Matching

Directly create and execute a matcher, returning either functions or direct values:

import { match, eq } from 'dmatch';

// Using a function
const resultFunction = match<string, string>('apple')
  .with(eq('apple'), () => 'It is an apple!')
  .execute();

console.log(resultFunction); // Outputs: 'It is an apple!'

// Using a direct value
const resultValue = match<string, string>('orange')
  .with(eq('orange'), 'It is an orange!')
  .execute();

console.log(resultValue); // Outputs: 'It is an orange!'

Reusable Matching

Preconfigure matchers for repetitive scenarios:

const fruitMatcher = match<string, string>()
  .with(eq('apple'), 'It is an apple!')
  .with(eq('orange'), 'It is an orange!')
  .finalize();

console.log(fruitMatcher('apple'));  // Outputs: 'It is an apple!'
console.log(fruitMatcher('orange')); // Outputs: 'It is an orange!'

Advanced Use Cases

With the flexibility dmatch offers, you can cater to a variety of complex scenarios:

Dynamic Pricing

Construct a dynamic pricing model based on various conditions:

import { match, withinRange } from 'dmatch';

const pricingModel = match<number, string>()
  .with(withinRange(0, 50), '$5')
  .with(withinRange(51, 100), '$10')
  .with(
    (val: number) => val > 100,
    (val: number) => `Custom price for ${val}`,
  )
  .finalize();

console.log(pricingModel(25));  // Outputs: '$5'
console.log(pricingModel(75));  // Outputs: '$10'
console.log(pricingModel(125)); // Outputs: 'Custom price for 125'

Custom Logic

Integrate complex logic seamlessly:

const customLogic = match<number, string>()
  .with(val => val < 0, 'Negative')
  .with(val => val === 0, 'Neutral')
  .with(val => val > 0, 'Positive')
  .finalize();

console.log(customLogic(-5)); // Outputs: 'Negative'
console.log(customLogic(0));  // Outputs: 'Neutral'
console.log(customLogic(5));  // Outputs: 'Positive'

Behaviors and Edge Cases

No Match and No Default

dmatch has a strict policy to ensure that patterns are matched correctly. If no matching pattern is found, and you haven't provided a default handler, dmatch will throw an error:

import { match } from 'dmatch';

const result = match<string, string>('hello')
  .with('hi', () => 'world')
  .execute();

// Throws an error: 'No match found and no default provided.'

License

dmatch is MIT licensed.

Thank you for using and supporting dmatch! For issues or suggestions, please open a GitHub issue.