Question

Please help me understand this recursive function…

var stack = Array;
function power(base, exponent){
    if ( exponent === 0 ) {
        return 1;
    } else {
        stack[exponent-1] = base * power(base, exponent - 1);
        return stack[exponent-1];
    }
}

I dont understand what

stack[exponent-1]

is doing

Answer 1

I did console log of stack[exponent-1] using

var stack = Array;
function power(base, exponent){
    if ( exponent === 0 ) {
        return 1;
    } else {
        stack[exponent-1] = base * power(base, exponent - 1);
        console.log(stack[exponent-1]);return stack[exponent-1];
    }
}

O/P:

power(2,5)
2
4
8
16
32

So function class recursively until exponent become 0 (nth call), then it will start returning results

first it will return 1     (because exponent is 0)
        then returns 2 * 1 (return of n call)
              then   2 * 2 (return of n-1 call) 
              then   2 * 4 (return of n-2 call) and so on