NavBarMenu.js

import React, { Component } from "react";

import Navbar from "react-bootstrap/Navbar"
import Nav from "react-bootstrap/Nav"
import NavDropdown from "react-bootstrap/NavDropdown"
import Form from "react-bootstrap/Form"
import FormControl from "react-bootstrap/FormControl"
import Button from "react-bootstrap/Button"

class NavBarMenu extends Component {
  constructor(props) {
    super(props);
    this.state = {};
  }
  render() {
    return (
      <div>
        <Navbar  expand="lg" className="navbar" variant="dark">
          <Navbar.Brand href="#home">Traffic Analysis</Navbar.Brand>
          <Navbar.Toggle aria-controls="basic-navbar-nav" />
          <Navbar.Collapse id="basic-navbar-nav">
            <Nav className="mr-auto">
              <Nav.Link href="/" >Home</Nav.Link>

              <Nav.Link href="/onedaygraph">Road Traffic</Nav.Link>

              <NavDropdown title="Dropdown" id="basic-nav-dropdown">
                <NavDropdown.Item href="#action/3.1">Action</NavDropdown.Item>
                <NavDropdown.Item href="#action/3.2">
                  Another action
                </NavDropdown.Item>
                <NavDropdown.Item href="#action/3.3">
                  Something
                </NavDropdown.Item>
                <NavDropdown.Divider />
                <NavDropdown.Item href="#action/3.4">
                  Separated link
                </NavDropdown.Item>
              </NavDropdown>
            </Nav>

          </Navbar.Collapse>
        </Navbar>
      </div>
    );
  }
}

export default NavBarMenu;