Function: juxt()

Call Signature

juxt<Fns>(fns): (...args) => ReturnTypes<Fns>

Defined in: function/juxt/index.ts:67

Creates a function that applies multiple functions to the same input and returns all results as an array.

The juxt combinator (short for "juxtaposition") applies each function to the input value and collects all results in an array, preserving the order.

This is useful when you need to apply multiple transformations to the same value and keep all the results.

Type Parameters

Fns

Fns extends readonly (...args) => any[]

Parameters

fns

Fns

Returns

(...args): ReturnTypes<Fns>

Parameters

args

...Parameters<Fns[0]>

Returns

ReturnTypes<Fns>

Examples

const analyze = juxt([
  (nums: number[]) => nums.length,
  (nums: number[]) => Math.min(...nums),
  (nums: number[]) => Math.max(...nums),
  (nums: number[]) => nums.reduce((a, b) => a + b, 0) / nums.length
])

analyze([1, 2, 3, 4, 5])
// => [5, 1, 5, 3]
//    [length, min, max, average]

// Extract multiple fields from an object
interface User { id: string; name: string; email: string; role: string }

const getUserSummary = juxt([
  (user: User) => user.id,
  (user: User) => user.name,
  (user: User) => user.role
])

getUserSummary({ id: '1', name: 'Alice', email: 'alice@example.com', role: 'admin' })
// => ['1', 'Alice', 'admin']

// Data-first
const result = juxt([
  (s: string) => s.toUpperCase(),
  (s: string) => s.toLowerCase(),
  (s: string) => s.length
], 'Hello')
// => ['HELLO', 'hello', 5]

// In a pipe
pipe(
  getUserInput(),
  juxt([
    (input) => input.trim(),
    (input) => input.length,
    (input) => input.split(' ').length
  ])
)
// => [trimmedInput, totalLength, wordCount]

Call Signature

juxt<Fns>(fns, ...args): ReturnTypes<Fns>

Defined in: function/juxt/index.ts:70

Creates a function that applies multiple functions to the same input and returns all results as an array.

The juxt combinator (short for "juxtaposition") applies each function to the input value and collects all results in an array, preserving the order.

This is useful when you need to apply multiple transformations to the same value and keep all the results.

Type Parameters

Fns

Fns extends readonly (...args) => any[]

Parameters

fns

Fns

args

...Parameters<Fns[0]>

Returns

ReturnTypes<Fns>

Examples

const analyze = juxt([
  (nums: number[]) => nums.length,
  (nums: number[]) => Math.min(...nums),
  (nums: number[]) => Math.max(...nums),
  (nums: number[]) => nums.reduce((a, b) => a + b, 0) / nums.length
])

analyze([1, 2, 3, 4, 5])
// => [5, 1, 5, 3]
//    [length, min, max, average]

// Extract multiple fields from an object
interface User { id: string; name: string; email: string; role: string }

const getUserSummary = juxt([
  (user: User) => user.id,
  (user: User) => user.name,
  (user: User) => user.role
])

getUserSummary({ id: '1', name: 'Alice', email: 'alice@example.com', role: 'admin' })
// => ['1', 'Alice', 'admin']

// Data-first
const result = juxt([
  (s: string) => s.toUpperCase(),
  (s: string) => s.toLowerCase(),
  (s: string) => s.length
], 'Hello')
// => ['HELLO', 'hello', 5]

// In a pipe
pipe(
  getUserInput(),
  juxt([
    (input) => input.trim(),
    (input) => input.length,
    (input) => input.split(' ').length
  ])
)
// => [trimmedInput, totalLength, wordCount]