为数组分配一个键，并将其按名称和电子邮件分组到一个数组中

function groupByEmail(arr) {
  var result = [];
  
  for (var i = 0; i < arr.length; i++) {
    var current = arr[i];
    var key = current.key;
    var name = current.name;
    var email = current.email;
    
    var found = false;
    
    for (var j = 0; j < result.length; j++) {
      if (result[j].key === key) {
        result[j].names.push(name);
        result[j].emails.push(email);
        found = true;
        break;
      }
    }
    
    if (!found) {
      result.push({
        key: key,
        names: [name],
        emails: [email]
      });
    }
  }
  
  return result;
}