// declare function arraySum
function arraySum(i) {
// var curentVal will hold current value of i[j] member
// at first value of sum is ZERO
var sum = 0;
    // i will be an array, containing integers, strings and/or arrays like itself.
    // Sum all the integers you find, anywhere in the nest of arrays.

    for(var j = 0; j < i.length; j++) {
        // curentVal = i[j];
// if curentVal of i[j] is Array
        if(i[j] instanceof Array) {
            sum += arraySum(i[j]);
        } else if (typeof i[j] === 'number') {
            sum += i[j];
        }
    }
    return sum;
}

console.log(arraySum([[1,2,false],'4','5']));    // 3
console.log(arraySum([[1,2,3],4,5]));            // 15
console.log(arraySum([[[[[[[[[1]]]]]]]], 1]));    // 2