@anilkumarthakur/match
Advanced tools
PHP-style match expressions for JavaScript/TypeScript with 100% type safety and comprehensive test coverage.
@anilkumarthakur/match brings the power and elegance of PHP's match expression to the JavaScript/TypeScript world. It provides a clean, type-safe alternative to complex switch statements and nested if-else logic.
✨ Type-Safe: Full TypeScript support with generic types for subject and result
🎯 Readable: Clean, expressive syntax inspired by PHP match expressions
🚀 Fast: Efficient equality-based matching using JavaScript's Map
📦 Lightweight: Zero dependencies, only ~0.5KB gzipped (ES module)
🧪 Well-Tested: 127 comprehensive tests with 100% code coverage
đź”— Chainable: Fluent API for method chaining
🌍 Cross-Platform: Works in Node.js and browsers (ESM + UMD)
npm install @anilkumarthakur/match
yarn add @anilkumarthakur/match
bun add @anilkumarthakur/match
import { match } from '@anilkumarthakur/match'
const result = match('success')
.on('success', () => 'Operation successful!')
.on('error', () => 'Something went wrong')
.otherwise(() => 'Unknown status')
console.log(result) // "Operation successful!"
match<TSubject, TResult>(subject: TSubject): MatcherCreates a new match expression for the given subject value.
Parameters:
subject - The value to match against (any type)Returns: A Matcher instance for method chaining
Example:
const matcher = match(statusCode)
on(value: TSubject, handler: () => TResult): MatcherAdds a case to match against. Uses strict equality (===) for comparison.
Parameters:
value - The value to matchhandler - Function returning the result if matchedReturns: The matcher instance (for chaining)
Example:
match(status)
.on(200, () => 'Success')
.on(404, () => 'Not Found')
onAny(values: readonly TSubject[], handler: () => TResult): MatcherAdds multiple values that all map to the same handler (simulates PHP's comma-separated cases).
Parameters:
values - Array of values to matchhandler - Function to execute if any value matchesReturns: The matcher instance (for chaining)
Example:
match(status)
.onAny([200, 201, 202], () => 'Success')
.onAny([400, 401, 403], () => 'Client Error')
otherwise(handler: () => TResult): TResultSets the default handler and executes the match. Returns immediately with the result.
Parameters:
handler - Function to execute if no cases matchReturns: The result from matched handler or default handler
Throws: UnhandledMatchError if no match found and no default provided
Example:
const result = match(value)
.on('expected', () => 'matched')
.otherwise(() => 'default')
default(handler: () => TResult): TResultPHP-compatible alias for otherwise(). Identical behavior.
Example:
const result = match(value)
.on('expected', () => 'matched')
.default(() => 'default')
valueOf(): TResultExecutes the match without a default handler. Throws if no match found.
Returns: The result from matched handler
Throws: UnhandledMatchError if no match found
Example:
const result = match('test')
.on('test', () => 'matched')
.valueOf() // Must have matched something
UnhandledMatchErrorCustom error thrown when no case matches and no default handler is provided.
Properties:
name - "UnhandledMatchError"message - Contains the unmatched valueExample:
try {
match('foo')
.on('bar', () => 'bar')
.valueOf()
} catch (error) {
if (error instanceof UnhandledMatchError) {
console.error('No match found for:', error.message)
}
}
import { match } from '@anilkumarthakur/match'
const getRole = (role: string) => {
return match(role)
.on('admin', () => 'Full access')
.on('user', () => 'Limited access')
.on('guest', () => 'Read-only access')
.otherwise(() => 'Unknown role')
}
console.log(getRole('admin')) // "Full access"
const handleResponse = (statusCode: number) => {
return match(statusCode)
.on(200, () => 'OK')
.onAny([201, 202, 204], () => 'Created/Accepted')
.on(400, () => 'Bad Request')
.on(401, () => 'Unauthorized')
.on(404, () => 'Not Found')
.on(500, () => 'Server Error')
.otherwise(() => 'Unknown Status')
}
console.log(handleResponse(200)) // "OK"
console.log(handleResponse(201)) // "Created/Accepted"
console.log(handleResponse(999)) // "Unknown Status"
const showNotification = (type: string, message: string) => {
const styling = match(type)
.on('success', () => ({ color: 'green', icon: 'âś“' }))
.on('error', () => ({ color: 'red', icon: 'âś—' }))
.on('warning', () => ({ color: 'orange', icon: 'âš ' }))
.on('info', () => ({ color: 'blue', icon: 'â„ą' }))
.otherwise(() => ({ color: 'gray', icon: '•' }))
return `[${styling.icon}] ${message}`
}
console.log(showNotification('success', 'Saved!')) // "[âś“] Saved!"
console.log(showNotification('error', 'Failed!')) // "[âś—] Failed!"
const getUserStatus = (userId: string, status: string) => {
return match(userId)
.on('admin', () => {
return match(status)
.on('active', () => 'Admin is active')
.on('inactive', () => 'Admin is inactive')
.otherwise(() => 'Admin status unknown')
})
.on('user', () => {
return match(status)
.on('active', () => 'User is active')
.otherwise(() => 'User is inactive')
})
.otherwise(() => 'User not found')
}
console.log(getUserStatus('admin', 'active')) // "Admin is active"
console.log(getUserStatus('user', 'active')) // "User is active"
console.log(getUserStatus('guest', 'active')) // "User not found"
type LogLevel = 'debug' | 'info' | 'warn' | 'error'
const getLogColor = (level: LogLevel): string => {
return match(level)
.on('debug', () => 'gray')
.on('info', () => 'blue')
.on('warn', () => 'yellow')
.on('error', () => 'red')
.otherwise(() => 'white')
}
console.log(getLogColor('info')) // "blue"
const getUserMessage = (age: number, isPremium: boolean) => {
return match(true)
.on(age < 13, () => 'Not eligible')
.on(age >= 13 && age < 18, () => 'Teen user')
.on(age >= 18 && !isPremium, () => 'Free user')
.on(age >= 18 && isPremium, () => 'Premium user')
.otherwise(() => 'Unknown')
}
console.log(getUserMessage(25, true)) // "Premium user"
console.log(getUserMessage(16, false)) // "Teen user"
const daysInMonth = (month: string, year: number): number => {
const isLeap = (y: number) => y % 4 === 0 && (y % 100 !== 0 || y % 400 === 0)
return match(month.toLowerCase().slice(0, 3))
.on('jan', () => 31)
.on('feb', () => (isLeap(year) ? 29 : 28))
.on('mar', () => 31)
.on('apr', () => 30)
.on('may', () => 31)
.on('jun', () => 30)
.on('jul', () => 31)
.on('aug', () => 31)
.on('sep', () => 30)
.on('oct', () => 31)
.on('nov', () => 30)
.on('dec', () => 31)
.otherwise(() => {
throw new Error('Invalid month')
})
}
console.log(daysInMonth('February', 2024)) // 29 (leap year)
console.log(daysInMonth('February', 2025)) // 28
$result = match($status) {
'success', 'ok' => 'All good',
'error', 'fail' => 'Something went wrong',
default => 'Unknown'
};
const result = match(status)
.onAny(['success', 'ok'], () => 'All good')
.onAny(['error', 'fail'], () => 'Something went wrong')
.otherwise(() => 'Unknown')
The library supports matching on any JavaScript type using strict equality (===):
Full TypeScript support with automatic type inference:
// Explicit types
const result = match<string, number>('test')
.on('test', () => 123)
.otherwise(() => 456)
// Inferred types
const result2 = match('test')
.on('test', () => 'result') // Inferred as string result
.otherwise(() => 'default')
// Union types
type Status = 'success' | 'pending' | 'error'
const result3 = match<Status, string>('success')
.on('success', () => 'Done')
.on('pending', () => 'In progress')
.on('error', () => 'Failed')
.otherwise(() => 'Unknown')
The library includes 127 comprehensive tests with 100% code coverage:
# Run all tests
npm test
# Run with coverage
npm run test:coverage
# Watch mode
npm test -- --watch
Test categories:
Works in all modern browsers and Node.js 14+:
Contributions are welcome! Please feel free to submit issues and pull requests.
# Install dependencies
npm install
# Run tests
npm test
# Build
npm run build
# Lint and format
npm run lint-format
MIT - See LICENSE for details
See CHANGELOG.md for release history and updates.
FAQs
PHP-style match expressions for JavaScript/TypeScript
We found that @anilkumarthakur/match demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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