Character Occurrences Counter of a string

OccCounter_V2.js

function withAMap(str) {
    // A map for the character=>count mappings
    const counts = new Map();

    // Loop through the string...
    for (const ch of str) {
        // Get the count for it, if we have one; we'll get `undefined` if we don't
        // know this character yet. Using nullish coalescing (`??`), we can turn
        // that `undefined` into a `0`. (In obsolete environments that don't
        // support nullish coalescing, for this use case we could use the logical
        // OR operator [`||`] instead to use `0` instead of any falsy value, since
        // A) `undefined` is falsy, and B) None of the count values we're tracking
        // will be falsy because they're all non-zero. For some other use cases,
        // we'd need to use a conditional testing `undefined` explicitly.)
        const count = counts.get(ch) ?? 0;

        // Add one and store the result
        counts.set(ch, count + 1);
    }

    // Show the counts
    for (const [ch, count] of counts) {
        console.log(`"${ch}" count: ${counts.get(ch)}`);
    }
}

function withAnObject(str) {
    // An object for the character=>count mappings
    // We use `Object.create(null)` so the object doesn't have any inherited properties
    const counts = Object.create(null);

    // Loop through the string...
    for (const ch of str) {
        // Get the count for it, if we have one; we'll get `undefined` if we don't
        // know this character yet. Using nullish coalescing (`??`), we can turn
        // that `undefined` into a `0`. (In obsolete environments that don't
        // support nullish coalescing, for this use case we could use the logical
        // OR operator [`||`] instead to use `0` instead of any falsy value, since
        // A) `undefined` is falsy, and B) None of the count values we're tracking
        // will be falsy because they're all non-zero. For some other use cases,
        // we'd need to use a conditional testing `undefined` explicitly.)
        const count = counts[ch] ?? 0;

        // Add one and store the result
        counts[ch] = count + 1;
    }

    // Show the counts
    for (const ch in counts) {
        console.log(`"${ch}" count: ${counts[ch]}`);
    }
}

const str = "abc321";
console.log("With a Map:");
withAMap(str);
console.log("With an object:");
withAnObject(str);




//source
//https://stackoverflow.com/questions/19480916/count-number-of-occurrences-for-each-char-in-a-string
//https://stackoverflow.com/a/19480979/13861187