Solution to Day 1 of 7 Days of JS

First of all, we have a functional solution, not the best solution (it may take some time to run with large numbers), but a solution at least:

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

console.log(factorial(5))

The good thing is that is pretty easy to read.

Now, a better solution would be something like this:

function factorial(n)\{
  let j = 1;
  for (let i = 1; i <= n; i++)\{
    j = j * i;
  }
  return j;
}

console.log(factorial(5))

An imperative solution using a for loop. This makes our function run faster.

Now let’s see the average function. First of all, a solution using a for loop:

function average(array) \{
  let count = array.length;
  if (count == 0)\{
    return 0;
  } else \{
    var sum = 0;
    for (var i = 0; i < count; i++) \{
    sum = sum + array[i];
  }
  return sum / count;
  }
}

console.log(average([2,4]))

I also made it using the reduce() method and an arrow function. Something weird came out:

function average(array) \{
  let count = array.length;
  if (count == 0)\{
    return 0;
  } else \{
     return array.reduce( (a,b) => a + b) / count;
  }

}

console.log(average([2,5,2]));

That’s not very readable, so I prefer the first solution, which btw runs faster.

Both solutions have if and else statements, and you probably noticed why: to return 0 when the input is an empty array, and not some weird error, or the good ol’ NaN.

Any questions? Leave a comment!