Fast least significant bit first bit array conversion in Javascript

lsb_first_convert.js

function numToBits(num, length=8)
{
  const bits = Array(length)
  for (let i=0; i<length; i++)
  {
    bits[i] = n >> i & 1
  }
  return bits
}

function bitsToNum(bits)
{
  let num = 0
  for (let i=0; i<bits.length; i++)
  {
    num = num << 1 | bits[i]
  }
  return num
}