JSFiddle - React, Tailwind, and code Playground

HTML

<html>
  <head>
    <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script>
  </head>
  <body>
    <div id="map" style="width: 300px; height: 300px"></div>
    <table><tr>
      <td><div id="placemark_b" onclick="gMap.initFeature('placemark')"/></td>
      <td><div id="line_b" onclick="gMap.initFeature('line')"/></td>
    </tr></table>
    <script type="text/javascript">
      initialize();
    </script>
  </body>
</html>

JavaScript

var map;
// Update
var btn1=document.createElement('div');
btn1.id="c_placemark_b";
var btn2=document.createElement('div');
btn2.id="c_line_b";


var gMap = {
    buttons: {
        $line: null,
        $placemark: null
    },

    Feature: function(type){
        this[type]();
    },

    initFeature: function(type){
        new gMap.Feature(type);
    },

    isSelected: function(el){
       return (el.className == "selected"); 
    },

    select: function (buttonId){
        gMap.buttons.$line.className="unselected";
        gMap.buttons.$placemark.className="unselected";
        document.getElementById(buttonId).className="selected";
    }
}
// Update
gMap.Feature.prototype.line = function() {
    gMap.select('line_b');
    btn1.className="unselected";
    btn2.className="selected";
}
// Update
gMap.Feature.prototype.placemark = function() {
    gMap.select("placemark_b");
    btn2.className="unselected";
    btn1.className="selected";
}

function initialize() {
    map = new google.maps.Map(document.getElementById('map'));
    map.setCenter(new google.maps.LatLng(48.77565,9.181802));
    map.setZoom(12);
    map.setMapTypeId( google.maps.MapTypeId.ROADMAP );

    gMap.buttons.$line = document.getElementById("line_b");
    gMap.buttons.$placemark = document.getElementById("placemark_b");
    
    // Update
    var controlDiv = document.createElement('div');
    var table=document.createElement('TABLE');
    var tbdy=document.createElement('TBODY');
    
    var tr=document.createElement('TR');
    
    var td1=document.createElement('TD');
    td1.appendChild(btn1);
    
    var td2=document.createElement('TD');
    td2.appendChild(btn2);

    tr.appendChild(td1);
    tr.appendChild(td2);
    tbdy.appendChild(tr);
    table.appendChild(tbdy);
    controlDiv.appendChild(table);

    google.maps.event.addDomListener(btn1, 'click', function() {
        btn2.className="unselected";
        gMap.initFeature('placemark');
        this.className="selected";
       ...