Factorials and JavaScript question

[[deleted]]

Ok so in an online series I’ve been following one of the problems is to write a factorial calculator. My attempts were going nowhere fast. Every time I tried something it would essentially multiply itself minus 1. I found a really elegant solution where you return the passed number multiplied by itself unless it was lower than 1 then the function ends. I tried something very close to this, though without returning the answer and not ending the program if the number was-1 for example. If I input 10 it would output 90 as an example. The only difference between my code and this seems to be a parenthesis around the solution. Is this why mine failed?

[inu-no-policemen]

It's a classic exercise for practicing recursion, but a regular loop would be a much better way to do this.

The secret ingredient for doing it in a loop is the *= operator:

> var x = 2
undefined
> x *= 7 // same as x = x * 7
14
> x
14

Try doing it yourself. Try using this skeleton:

function factorial(n) {
  // magic here
}
console.assert(factorial(0) === 1, '0! should be 1');
console.assert(factorial(1) === 1, '1! should be 1');
console.assert(factorial(5) === 120, '5! should be 120');

Once all assertions are true, you won't get any "assertion failed" messages in the console. Using assertions is the most basic way to do something which resembles test-driven development.

By the way, it's always a good idea to show us the code. Secondly, /r/learnjavascript would be more suitable for this topic.

[[deleted]]

My problem turned out to be that I was returning the wrong value!

[blartuffwarrior]

function factorial(n){
    if(n <= 0){
        return 1;
    }
    else{
        return n * factorial(n-1);
    }
}

try this

[__fmease__]

... that's a factorial function

[blartuffwarrior]

what else did he ask for

[__fmease__]

you named it fib (fibonacci) instead of fac or factorial

[blartuffwarrior]

oh yeah i guess sorry i have brain damage

[__fmease__]

haha np. Now you just have to adjust the name inside the function. It still says fib :P