JavaScript/Algorithms/EucledianGCD.js

function euclideanGCDRecursive(first, second) {
    /*
    Calculates GCD of two numbers using Euclidean Recursive Algorithm
    :param first: First number
    :param second: Second number
    :return: GCD of the numbers
    */
    if (second === 0) {
        return first;
    } else {
        return euclideanGCDRecursive(second, (first % second));
    }
}

function euclideanGCDIterative(first, second) {
    /*
    Calculates GCD of two numbers using Euclidean Iterative Algorithm
    :param first: First number
    :param second: Second number
    :return: GCD of the numbers
    */
    while (second !== 0) {
        let temp = second;
        second = first % second;
        first = temp;
    }
    return first;
}

function main() {
    let first = 20;
    let second = 30;
    console.log('Recursive GCD for %d and %d is %d', first, second, euclideanGCDRecursive(first, second));
    console.log('Iterative GCD for %d and %d is %d', first, second, euclideanGCDIterative(first, second));
}

main();