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Function: partial()

Call Signature​

partial<Args, R>(fn): (...args) => R

Defined in: function/partial/index.ts:40

Creates a partially applied function by pre-filling arguments from the left.

Returns a new function that, when called, invokes the original function with the pre-filled arguments followed by any new arguments.

Type Parameters​

Args​

Args extends readonly any[]

R​

R

Parameters​

fn​

(...args) => R

Returns​

(...args): R

Parameters​

args​

...Args

Returns​

R

Examples​

const greet = (greeting: string, name: string) => `${greeting}, ${name}!`

const sayHello = partial(greet, 'Hello')
sayHello('Alice')    // => 'Hello, Alice!'
sayHello('Bob')      // => 'Hello, Bob!'
// Multiple arguments
const multiply = (a: number, b: number, c: number) => a * b * c

const double = partial(multiply, 2)
double(3, 4)         // => 24  (2 * 3 * 4)

const quadruple = partial(multiply, 2, 2)
quadruple(5)         // => 20  (2 * 2 * 5)
// Creating specialized functions
const log = (level: string, module: string, message: string) =>
  `[${level}] ${module}: ${message}`

const logError = partial(log, 'ERROR')
const logUserError = partial(log, 'ERROR', 'UserModule')

logUserError('Invalid input')  // => '[ERROR] UserModule: Invalid input'

Call Signature​

partial<Args, R>(fn, ...prefilledArgs): (...args) => R

Defined in: function/partial/index.ts:43

Creates a partially applied function by pre-filling arguments from the left.

Returns a new function that, when called, invokes the original function with the pre-filled arguments followed by any new arguments.

Type Parameters​

Args​

Args extends readonly any[]

R​

R

Parameters​

fn​

(...args) => R

prefilledArgs​

...any[]

Returns​

(...args): R

Parameters​

args​

...any[]

Returns​

R

Examples​

const greet = (greeting: string, name: string) => `${greeting}, ${name}!`

const sayHello = partial(greet, 'Hello')
sayHello('Alice')    // => 'Hello, Alice!'
sayHello('Bob')      // => 'Hello, Bob!'
// Multiple arguments
const multiply = (a: number, b: number, c: number) => a * b * c

const double = partial(multiply, 2)
double(3, 4)         // => 24  (2 * 3 * 4)

const quadruple = partial(multiply, 2, 2)
quadruple(5)         // => 20  (2 * 2 * 5)
// Creating specialized functions
const log = (level: string, module: string, message: string) =>
  `[${level}] ${module}: ${message}`

const logError = partial(log, 'ERROR')
const logUserError = partial(log, 'ERROR', 'UserModule')

logUserError('Invalid input')  // => '[ERROR] UserModule: Invalid input'