taylor expansion sin & factorial javascript

sin.js

factorial = (x) =>
{
	let total = 1;
	for(let i = 1; i <= x; i+=2)
	{
		if(i + 1 > x)
			total *= i;
		else
			total *= (i * (i + 1));
	}
	return total;
};

sin = (x) =>
{
	let s = x;
	let n = 3;
	for(let i = 0; i < 32; ++i)
	{
		if(i % 2 == 0)
			s -= Math.pow(x, n) / factorial(n);
		else
			s += Math.pow(x, n) / factorial(n);
		n += 2;
	}
	return s;
};