once

function

Creates a function that is restricted to invoking func once.

Installation

Import

import { once } from '@tulx/utils';

Source Code

Implementation

/**
 * Creates a function that is restricted to invoking func once.
 *
 * @param func - The function to restrict.
 * @returns Returns the new restricted function.
 *
 * @example
 * ```ts
 * const initialize = once(() => console.log('initialized'));
 * initialize(); // 'initialized'
 * initialize(); // Nothing happens
 * ```
 */
// eslint-disable-next-line @typescript-eslint/no-explicit-any
export function once<T extends (...args: any[]) => any>(
  func: T
): (...args: Parameters<T>) => ReturnType<T> {
  let called = false;
  let result: ReturnType<T>;

  return function (this: unknown, ...args: Parameters<T>): ReturnType<T> {
    if (!called) {
      called = true;
      result = func.apply(this, args) as ReturnType<T>;
    }
    return result!;
  };
}

Example

import { once } from '@tulx/utils';

const initialize = once(() => console.log('initialized'));
initialize(); // 'initialized'
initialize(); // Nothing happens

Related Functions

after

The opposite of before; this method creates a function that invokes func once it's called n or more times.

ary

Creates a function that invokes func, with up to n arguments, ignoring any additional arguments.

before

Creates a function that invokes func, with the this binding and arguments of the created function, while it's called less than n times.

bind

Creates a function that invokes func with the this binding of thisArg and partials prepended to the arguments it receives.

bindKey

Creates a function that invokes the method at object[key] with partials prepended to the arguments it receives.

curry

Creates a function that accepts arguments of func and either invokes func returning its result, or returns a function that accepts the remaining arguments.