30 Days of Javascript 2 - Counter

Given an integer n, return a counter function. This counter function initially returns n and then returns 1 more than the previous value every subsequent time it is called (n, n + 1, n + 2, etc).

Example 1:

Input: n = 10 [“call”,”call”,”call”] Output: [10,11,12] Explanation: counter() = 10 // The first time counter() is called, it returns n. counter() = 11 // Returns 1 more than the previous time. counter() = 12 // Returns 1 more than the previous time. Example 2:

Input: n = -2 [“call”,”call”,”call”,”call”,”call”] Output: [-2,-1,0,1,2] Explanation: counter() initially returns -2. Then increases after each sebsequent call.

/**
 * @param {number} n
 * @return {Function} counter
 */
var createCounter = function (n) {
  return function () {
    return n++;
  };
};

/**
 * const counter = createCounter(10)
 * counter() // 10
 * counter() // 11
 * counter() // 12
 */

The counter function takes an integer n as input and returns a new function. The returned function, when invoked, increments n by 1 and returns the updated value. In the example usage, an array calls contains the string “call” for each invocation. The counter function is called n number of times, and each time it is called, the returned value is pushed into the result array.