2666-allow-one-function-call.js

/**
 * 2666. Allow One Function Call
 * https://leetcode.com/problems/allow-one-function-call/
 * Difficulty: Easy
 *
 * Given a function fn, return a new function that is identical to the original function except
 * that it ensures fn is called at most once.
 *
 * - The first time the returned function is called, it should return the same result as fn.
 * - Every subsequent time it is called, it should return undefined.
 */

/**
 * @param {Function} fn
 * @return {Function}
 */
var once = function(fn) {
  return (...args) => fn && [fn(...args), fn = undefined][0];
};