Solving Leetcode 30 Days of JavaScript study plan problems

Problem:

Write a function createCounter. It should accept an initial integer init. It should return an object with three functions.

The three functions are:

• increment() increases the current value by 1 and then returns it.

• decrement() reduces the current value by 1 and then returns it.

• reset() sets the current value to init and then returns it.

Example 1:

Input: init = 5, calls = ["increment","reset","decrement"]
Output: [6,5,4]
Explanation:
const counter = createCounter(5);
counter.increment(); // 6
counter.reset(); // 5
counter.decrement(); // 4

Example 2:

Input: init = 0, calls = ["increment","increment","decrement","reset","reset"]
Output: [1,2,1,0,0]
Explanation:
const counter = createCounter(0);
counter.increment(); // 1
counter.increment(); // 2
counter.decrement(); // 1
counter.reset(); // 0
counter.reset(); // 0

Solution JavaScript:

/**
 * @param {integer} init
 * @return { increment: Function, decrement: Function, reset: Function }
 */
function createCounter(init) {
  const currentCount = init;
  return {
    increment: () => {
      return ++init;
    },
    decrement: () => {
      return --init;
    },
    reset: () => {
      init = currentCount;
      return init;
    },
  };

}

Initialize a variable for currentCount to be the initial value of the counter before it's changed

Inside the createCounter function, returns an object that has three properties increment, decrement, and reset :

• increment: Holds a function that takes the current init value and increments it by one

• decrement: This function takes the current value of init decrements it by 1 and returns it

• reset: This function sets init to be the currentCount. which was the first value before any increment and decrement.

This code essentially provides a simple way to perform these calculations in JavaScript code.