Given two arrays, the find an integer denoting the number of integers that are BOTH multiples of all numbers in the first array and factors of all numbers in the second array.

challenge1.js

function getBetweenTwoSets(a1, a2) {

    function gcd(a, b){
        while(b > 0){
            var temp = b;
            b = a % b;
            a = temp;
        }
        return a
    }
    
    function gcdArray(array){
        var result = array[0];
        for(var i = 1; i < array.length; i++){
            result = gcd(result, array[i])
        }
        return result;
    }
    
    function lcm(a, b){
        return a  * (b / gcd(a, b));
    }
    
    function lcmArray(array){
        var result = array[0];
        for(var i = 1; i < array.length; i++){
            result = lcm(result, array[i])
        }
        return result;
    }
    
    var l = lcmArray(a1);
    var r = gcdArray(a2);
    var count = 0;
    
    for(var i = 1; i*l <= r; i++){
        if(r % (l * i) == 0)
            count++
    }
    
    return count++;

}