JSFiddle - React, Tailwind, and code Playground

HTML

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<div id="map_canvas" style="height:400px;"></div>

JavaScript

var directionDisplay,
      directionsService = new google.maps.DirectionsService(),
      map,
      berlin = new google.maps.LatLng(52.524268, 13.406290000000013),
      potsdam = new google.maps.LatLng(52.3941887, 13.072690999999963);
      
      
      
  function ginit() {
    directionsDisplay = new google.maps.DirectionsRenderer();
    
    var myOptions = {
      zoom:12,
      mapTypeId: google.maps.MapTypeId.ROADMAP,
      center: berlin
    }
    map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
    directionsDisplay.setMap(map);
    calcRoute();
  }
  
  function calcRoute() {
    var start = berlin
    var end = potsdam
    var request = {
        origin:start, 
        destination:end,
        travelMode: google.maps.DirectionsTravelMode.DRIVING
    };
    directionsService.route(request, function(response, status) {
      if (status == google.maps.DirectionsStatus.OK) {
        directionsDisplay.setDirections(response);
        fx(response.routes[0]);
      }
    });
  }
  
  function fx(o)
  {
    if(o && o.legs)
    {
      for(l=0;l<o.legs.length;++l)
      {
        var leg=o.legs[l];
        for(var s=0;s<leg.steps.length;++s)
        {
          var step=leg.steps[s],
              a=(step.lat_lngs.length)?step.lat_lngs[0]:step.start_point,
              z=(step.lat_lngs.length)?step.lat_lngs[1]:step.end_point,
              dir=((Math.atan2(z.lng()-a.lng(),z.lat()-a.lat())*180)/Math.PI)+360,
              ico=((dir-(dir%3))%120);
              new google.maps.Marker({
                position: a,
                icon: new google.maps.MarkerImage('http://maps.google.com/mapfiles/dir_'+ico+'.png',
                                            new google.maps.Size(24,24),
                                            new google.maps.Point(0,0),
                                            new google.maps.Point(12,12)
                                           ),
          map: map,
          title:...