My Nodejs function is returning an Undefined instead of a value

Question

`

function summation(num, args=0) {

    let value = args;
    value += num;
    num -= 1;
    if(num == 0){
        return value;
    }
    summation(num, value);

}
console.log(summation(3));

the function summation is sort of a factorial that calculates numbers from 1 to num and adds them to total. The function calls itself and keeps adding the subsequent numbers from zero to the provided number until its zero, then it returns value. if I pass 3 into the function, the function should return 6 however, im getting an undefined. I used a breakpoint in vs code to check what exactly the function is doing, and 6 is actually stored in value at the last point however, the 6 suddenly turns into an undefined right on the return statement.

Answer 1

You need to return the result of summation when you call it, this should resolve the issue:

function summation(num, args=0) {

    let value = args;
    value += num;
    num -= 1;
    if(num == 0){
        return value;
    }
    return summation(num, value);
}

for(let i of [1,2,3,4]) {
    console.log(`Summation(${i}):`, summation(i));
}