Multiple of letters count in js

June 20, 2022

i have a task:
Count the number of letters “a” in text
Count the number of letters “o” in text
Write the result of multiplying the number of letters “a” and “o”.

is it possible to solve this task in a shorter way??

function countString(str, letter) {
  let count = 0;
  for (let i = 0; i < str.length; i++) {
    if (str.charAt(i) == letter) {
      count += 1;
    }
  }
  return count;
}

const string = hello my name is Ola.toLowerCase()
const letterToCheck = "o"
const letterToCheckTwo = "a"

const result = countString(string, letterToCheck);
const resultTwo = countString(string, letterToCheckTwo);


const total = result + resultTwo
console.log(total)

>Solution :

You can create an object that stores the count of all the characters and then you can compute the product using this object.

const str = "Avacado";
const charsCount = Array.prototype.reduce.call(
  str,
  (r, ch) => {
    const lowerCh = ch.toLowerCase()
    r[lowerCh] ??= r[lowerCh] || 0;
    r[lowerCh] += 1;
    return r;
  },
  {}
);

console.log(charsCount["o"] * charsCount["a"]);

Note: Array.prototype.reduce is a generic method, so it can be used with a string as well.