func ShiftLeft(b []byte) []byte {
    l := len(b)
    if l == 0 {
        panic("shiftLeft requires a non-empty buffer.")
    }

    output := make([]byte, l)

    overflow := byte(0)
    for i := int(l - 1); i >= 0; i-- {
        output[i] = b[i] << 1
        output[i] |= overflow
        overflow = (b[i] & 0x80) >> 7
    }

    return output
}

function makeEmpty(size) {


  var result = [];

  for (var i = 0; i < size; i++) {
    result.push(0x00);
  }

  return result;

}

function shiftLeft (b) {

  var len = b.length;

  if (len == 0) {
    throw 'shiftLeft requires a non-empty buffer';
  }

  var output = makeEmpty(len);

  var overflow = 0;

  for (var i = len - 1; i >= 0; i--) {
    output[i] = b[i] << 1;
    output[i] |= overflow;
    overflow = (b[i] & 0x80) >> 7;
  }

  return output;

}

function fromOctal(str) {

  var bytes = [parseInt(str, 2)];

  return bytes;

}

console.log(shiftLeft(fromOctal("10000000"))

output[i] = b[i] << 1;

output[i] = (b[i] << 1) & 0xFF;