Get a number without "tail" using charCode

I have the following problem:
when writing a number, I get a big tail. I know it’s related with bits, but how do I avoid this tail? We can’t use native methods and concatenations, parseInt, parseFloat, Number and etc.

function getNum(message) {
  const zero = "0".charCodeAt(0);
  const nine = "9".charCodeAt(0);
  const comma = ",".charCodeAt(0);
  let num = 0,
    factor = 1,
    numStarted = false;

  for (let i = message.length - 1; i >= 0; i--) {
    const charCode = message.charCodeAt(i);

    if (charCode >= zero && charCode <= nine) {
      num = num + (charCode - zero) * factor;
      factor *= 10;
      numStarted = true;
    } else if (numStarted && charCode === comma) {
      num /= factor;
      factor = 1;
    } else {
      numStarted = false;
    }
  }
  return num;
}

console.log(getNum("Today i spend a 56,02 USD, it's a lot for me."));

need result: 56,02.
my result: 56.019999999999996

>Solution :

It works if you keep the integer and the fractional part separate. Replace

else if (numStarted && charCode === comma) {
  num /= factor;
  factor = 1;
}

with

else if (numStarted && charCode === comma) {
  frac = num / factor;
  num = 0;
  factor = 1;
}

and

return num + frac;

at the end. Also initialize let frac = 0;