Solution to the "Bean Counting" exercise in Chapter 3 of "Eloquent JavaScript" by Marijn Haverbeke

countChar

// from https://eloquentjavascript.net/03_functions.html#i_3rsiDgC2do

/*
Write a function countBs that takes a string as its only argument 
and returns a number that indicates how many uppercase “B” characters
there are in the string.

Next, write a function called countChar that behaves like countBs,
except it takes a second argument that indicates the character that 
is to be counted (rather than counting only uppercase “B” characters).

Rewrite countBs to make use of this new function.
*/

const countChar = (string, character) => {
    let count = 0;
    string.split('').forEach((x) => {
        x === character ? count++ : null
    });
    return count;
};

const countCharUsingReduce = (string, character) => {
    return string.split('').reduce((accumulator, currentValue) => {
        currentValue === character ? accumulator++ : 0;
        return accumulator;
    }, 0);
};

const countBs = (string) => countChar(string, 'B');

console.log(countBs("BBC"));
// → 2
console.log(countChar("kakkerlak", "k"));
// → 4
console.log(countCharUsingReduce("kakkerlak", "k"));
// → 4