как подсчитать количество вхождений подстроки в строку на javascript

const countOccurrences = (str, substr) => str.split(substr).length - 1;

const mainStr = "abacabadabacaba";
const subStr = "aba";
const occurrences = countOccurrences(mainStr, subStr);
console.log(occurrences); // Output: 3

const countOccurrences = (str, substr) => {
    const regExp = new RegExp(substr, "g");
    return (str.match(regExp) || []).length;
}

const mainStr = "abacabadabacaba";
const subStr = "aba";
const occurrences = countOccurrences(mainStr, subStr);
console.log(occurrences); // Output: 3

const countOccurrences = (str, substr, count = 0) => {
    const index = str.indexOf(substr);
    if (index !== -1) {
        return countOccurrences(str.slice(index + substr.length), substr, count + 1);
    }
    return count;
}

const mainStr = "abacabadabacaba";
const subStr = "aba";
const occurrences = countOccurrences(mainStr, subStr);
console.log(occurrences); // Output: 3