F_A_8_Test_app/src/components/public/Header.js

import React from 'react';
import { Link } from "react-router-dom";
import * as routes from '../../constants/routes'

export default class Header extends React.Component {
    render() {
        return (
            <div className="row">
                <div className="container-fluid">
                    <nav class="navbar navbar-expand-lg navbar-dark bg-dark mb-2">
                        <a class="navbar-brand" href="#">Test.io</a>
                        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
                            <span class="navbar-toggler-icon"></span>
                        </button>

                        <div class="collapse navbar-collapse" id="navbarSupportedContent">
                            <ul class="navbar-nav mr-auto p-3">
                                <li class="nav-item active">
                                <Link onClick={this.handleClick} class="nav-link font-ci font-ci-bold" to={routes.HOME}>Home <span class="sr-only">(current)</span></Link>
                                </li>
                                <li class="nav-item">
                                <Link onClick={this.handleClick}  class="nav-link font-ci font-ci-bold"  to={routes.PROFILE}>Profile</Link>
                                </li>
                                <li class="nav-item">
                                <Link onClick={this.handleClick}  class="nav-link font-ci font-ci-bold "  to={routes.TESTS}>Tests</Link>
                                </li>
                                <li class="nav-item">
                                <Link onClick={this.handleClick}  class="nav-link font-ci font-ci-bold "  to={routes.CATEGORIES}>Catigories</Link>
                                </li>
                                {/* TODO: admin-only ! */}
                                <li class="nav-item dropdown">
                                    <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                                        Dropdown
                                    </a>
                                    <div class="dropdown-menu" aria-labelledby="navbarDropdown">
                                        <a class="dropdown-item" href="#">Action</a>
                                        <a class="dropdown-item" href="#">Another action</a>
                                        <div class="dropdown-divider"></div>
                                        <a class="dropdown-item" href="#">Something else here</a>
                                    </div>
                                </li>
                               
                            </ul>
                            <form class="form-inline my-2 my-lg-0">
                                <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search" />
                                <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
                            </form>
                        </div>
                    </nav>
                </div>
            </div>
        )
    }
}