forrecur.js

function forFn(n) {
    if(n === 0) return 1;
    var a = 1;
    for(var i = 0; i<n; i++) a = a * 2
    return a
}

function recursiveFn(n, m) {
    if(!m) return factRecursive(n, 1)
    if(n === 0) return m;
    return recursiveFn(n-1, m * 2);
}