Header.js

import React, { Component } from 'react';
import { Link } from 'react-router-dom';
import {
  Menu,
  Container,
  Button,
  Segment,
  Visibility,
  Image,
} from 'semantic-ui-react';
import { connect } from 'react-redux';
import { getUserData } from '../actions';
import KSZKlogo from './images/kszk_logo.svg';

const menuItems = [
  {
    text: 'Főoldal',
    to: '/home',
    prefix: <Image size='mini' src={KSZKlogo} style={{ marginRight: '1.5em' }} />,
    permissionLevel: 0,
  },
  {
    text: 'Hírek',
    to: '/news',
    prefix: '',
    permissionLevel: 0,
  },
  {
    text: 'Köreink',
    to: '/groups',
    prefix: '',
    permissionLevel: 0,
  },
  {
    text: 'Ütemterv',
    to: '/schedule',
    prefix: '',
    permissionLevel: 1,
  },
  {
    text: 'Statisztika',
    to: '/statistics',
    prefix: '',
    permissionLevel: 3,
  },
  {
    text: 'Jelentkezések',
    to: '/applications',
    prefix: '',
    permissionLevel: 3,
  },
  {
    text: 'Házi feladatok',
    to: '/homework',
    prefix: '',
    permissionLevel: 2,
  },
];

const FixedMenu = ({ user }) => (
  <Menu fixed='top' size='large' pointing>
    <Container>
      {menuItems.map((item, i) =>
        (user.permission >= item.permissionLevel ||
          (item.permissionLevel === 0)
          ?
            <Menu.Item key={i} as={Link} to={item.to}>{item.text}</Menu.Item>
          :
          null))}