This script used to try integrating ReactJs with pure Google Maps API with following tutorial from here -> https://bit.ly/2UCz0HS

ReactPureGmaps

import React, { Component, Fragment } from "react";
import "./App.css";

class App extends Component {
  componentDidMount() {
    this.renderMap();
  }

  renderMap = () => {
    loadScript(
      "https://maps.googleapis.com/maps/api/js?key=AIzaSyBNeksjt_QfncrS2CAgbajesDOvw02ulOs&callback=initMap"
    );
    window.initMap = this.initMap;
  };

  initMap = () => {
    new window.google.maps.Map(document.getElementById("map"), {
      center: { lat: -34.397, lng: 150.644 },
      zoom: 8
    });
  };

  render() {
    return (
      <Fragment>
        <h1>Simple Map</h1>
        <div id="map" />
      </Fragment>
    );
  }
}

function loadScript(url) {
  var index = window.document.getElementsByTagName("script")[0];
  var script = window.document.createElement("script");
  script.src = url;
  script.async = true;
  script.defer = true;
  index.parentNode.insertBefore(script, index);
}
export default App;