Convert a number to a string without using a one line cast (e.g. number + "")

floatToString

function floatToString(number) {
  function getDecimals(number) {
    if (!isFinite(number)) return 0;
    let exponent = 1;
    let p = 0;
    while (Math.round(number * exponent) / exponent !== number) {
      exponent *= 10;
      p++;
    }
    return p;
  }
  const decimals = getDecimals(number);

  // also is number length
  const decimalIndex = Math.floor(Math.log10(number)) + 1;

  let string = '';
  let numberTracker = number;

  function shiftFirstDigit(i) {
    const power = Math.pow(10, i);
    const digit = Math.floor(numberTracker / power);
    string += digit;
    numberTracker = Number((numberTracker - (digit * power)).toFixed(decimals));
  }

  // add digits to left of decimal
  for (let i = decimalIndex - 1; i >= 0; i--) {
    shiftFirstDigit(i);
  }

  if (decimals === 0) {
    return string
  }

  string += "."

  // convert to integer
  numberTracker = numberTracker * Math.pow(10, decimals)

  // add digits to right of decimal
  for (let i = decimals - 1; i >= 0; i--) {
    shiftFirstDigit(i);
  }

  return string
}

const result = floatToString(123.45);
console.log({ result })