Allow One Function Call.js

// 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.
 

// Example 1:

// Input: fn = (a,b,c) => (a + b + c), calls = [[1,2,3],[2,3,6]]
// Output: [{"calls":1,"value":6}]
// Explanation:
// const onceFn = once(fn);
// onceFn(1, 2, 3); // 6
// onceFn(2, 3, 6); // undefined, fn was not called
// Example 2:

// Input: fn = (a,b,c) => (a * b * c), calls = [[5,7,4],[2,3,6],[4,6,8]]
// Output: [{"calls":1,"value":140}]
// Explanation:
// const onceFn = once(fn);
// onceFn(5, 7, 4); // 140
// onceFn(2, 3, 6); // undefined, fn was not called
// onceFn(4, 6, 8); // undefined, fn was not called
 

// CODE

/**
 * @param {Function} fn
 * @return {Function}
 */
var once = function(fn) {
    let called = false 
    return function(...args){
        if (called){
            return undefined 
        }
       called = true 
       return fn(...args)
    }
};

/**
 * let fn = (a,b,c) => (a + b + c)
 * let onceFn = once(fn)
 *
 * onceFn(1,2,3); // 6
 * onceFn(2,3,6); // returns undefined without calling fn
 */