before

Creates a new function that limits the number of times a function can be called.

const limitedFunc = before(n, func);

Reference

before(n, func)

Use before when you want to limit a function to be executed only up to a specific number of times. The function will execute until the n-1-th call, and from the n-th call onwards, it will no longer execute.

import { before } from 'es-toolkit/function';

const beforeFn = before(3, () => {
  console.log('executed');
});

// Logs 'executed'
beforeFn();

// Logs 'executed'
beforeFn();

// Logs nothing
beforeFn();

// Logs nothing
beforeFn();

This is useful for tasks that should only be executed once, such as initialization or setup.

let initialized = false;

const initialize = before(2, () => {
  console.log('Initializing...');
  initialized = true;
});

// Logs 'Initializing...' and performs initialization
initialize();

// Does nothing as it's already initialized
initialize();

Parameters

• n (number): The maximum number of times the returned function can call func. If n is 0, func will not be called. If it's a positive integer, it will be called up to n-1 times.
• func (F): The function whose invocation count will be limited.

Returns

((...args: Parameters<F>) => ReturnType<F> | undefined): A new function that tracks the number of calls and executes func only up to the n-1-th call. Returns undefined for calls from the n-th onwards.

Throws

Throws an error when n is not an integer or is negative.