Javascript groupBy function

function groupBy(array, key) {
  return array.reduce(function(result, currentValue) {
    (result[currentValue[key]] = result[currentValue[key]] || []).push(currentValue);
    return result;
  }, {});
}


// counter
function groupBy(array, key) {
  return array.reduce(function(result, currentValue) {
    var group = currentValue[key];
    if (!result[group]) {
      result[group] = { count: 0, values: [] };
    }
    result[group].count++;
    result[group].values.push(currentValue);
    return result;
  }, {});
}


// inet_ntoa
function numberToIp(number) {
  var parts = [];
  for (var i = 3; i >= 0; i--) {
    parts[i] = number & 255;
    number = number >> 8;
  }
  return parts.join('.');
}