Return least and most significant bits of a number.

lsbAndMsb.js

function lsbMsb(bits) {
  if (!bits) return {lsb: undefined, msb: undefined};

  let lsb = 0;
  for (; lsb < 31 && (bits & 1) === 0; bits >>= 1) {
    lsb++;
  }

  let msb = lsb;
  for (bits >>= 1; msb < 31 && bits !== 0; bits >>= 1) {
    msb++;
  }

  return {lsb, msb};
}