JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maps.googleapis.com/maps/api/js"></script>
<div id="map"></div>
<div id="side">
<ol id="list"></ol>  
</div>

CSS

html, body {
        height: 98%;
        margin: 0;
        padding: 0;
      }
	 
	  #map {
		height: 100%;
		width:70%;
		float:left;
      }
	  #side{
	  height:100%;
	  width:25%;
	  float:left;
	  }

JavaScript

var map;

     
     	map = new google.maps.Map(document.getElementById('map'), {
     		center: {
     			lat: -27.2341789,
     			lng: 134.0797745
     		},
     		zoom: 4
     	});
     	google.maps.event.addListenerOnce(map, 'bounds_changed', function() {

     		var bounds = map.getBounds();
     		console.log(bounds)
     		var southWest = bounds.getSouthWest();
     		var northEast = bounds.getNorthEast();
     		var lngSpan = northEast.lng() - southWest.lng();
     		var latSpan = northEast.lat() - southWest.lat();
     		var len = 100,
     			i = 0,
     			mkrs = [];


     		for (i; i < len; i++) {
     			var pnt = new google.maps.LatLng(southWest.lat() + latSpan * Math.random(), southWest.lng() + lngSpan * Math.random());

     			var marker = new google.maps.Marker({
     				position: pnt,
     				map: map,
     				title: "Marker " + i
     			});
     			var myli = document.createElement("li");
     			myli.innerHTML = marker.title;
     			document.getElementById("list").appendChild(myli);
     			bounds.extend(pnt);
     			mkrs.push(marker);
     		}

     		map.fitBounds(bounds);

     		google.maps.event.addListener(map, 'bounds_changed', function() {
     			document.getElementById("list").innerHTML = "";
     			var mklen = mkrs.length,
     				a = 0,
     				bnds = map.getBounds();

     			for (a; a < mklen; a++) {
     				var themk = mkrs[a];
     				if (bnds.contains(themk.getPosition())) {
     					var myli = document.createElement("li");
     					myli.innerHTML = themk.title;
     					document.getElementById("list").appendChild(myli);
     				}
     			}
     		});
     	});