cie_cs_p3_floatingpoint_to_decimal.js

function toDecimal(mantissa_str, exponent_str) {
  const [sign_str, sig_str] = mantissa_str.split('.')
  const sign = sign_str === "1" ? -1 : 0
  const [ex_sign_str, ...ex_sig_arr] = exponent_str.split("")

  const ex_sign = ex_sign_str === '1' ? -1 * Math.pow(2, exponent_str.length - 1) : 0

  const ex_summed = ex_sign + ex_sig_arr.reverse().map(
    (bit, i) => bit === '1' ? Math.pow(2, i) : 0
  ).reduce((a, b) => a + b, 0)

  const summed = sign + sig_str.split("").map(
    (bit, i) => bit === '1' ? Math.pow(2, -1 * (i + 1)) : 0
  ).reduce((a, b) => a + b, 0)

  return summed * Math.pow(2, ex_summed)
}

console.log(toDecimal("1.1111111", "100"))