bitCounter

gistfile1.txt

function addBinary( strA, strB ) {
  let result = '';
  let carry = false;

  for ( let i = Math.max( strA.length, strB.length ); i > -1; i-- ) {
    result += addBits( strA[ i ] ? parseInt( strA[ i ] ) : 0, strB[ i ] ? parseInt( strB[ i ] ) : 0 );
  }

  return result;

  function addBits( bitA = 0, bitB = 0 ) {

    if ( ( carry && ( ( bitA && bitB ) || ( !bitA && !bitB ) ) ) || ( ( bitA || bitB ) && ( !bitA || !bitB ) ) ) {
      return '1';
    }

    carry = ( bitA && bitB ) || ( carry && ( bitA || bitB ) );

    return '0';
  }
}