JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maps.googleapis.com/maps/api/js?libraries=visualization"></script>
<div id="map-canvas"></div>

CSS

#map-canvas {
    width: 300px;
    height: 300px;
}

JavaScript

// initialize heatmap data
var heatmapData = [
  new google.maps.LatLng(35.685175, 139.752799),
  {location: new google.maps.LatLng(35.65858, 139.745433), weight: 8},
  {location: new google.maps.LatLng(35.710063, 139.8107), weight: 5}
];

// initialize map
var map = new google.maps.Map(document.getElementById('map-canvas'), {
    center: new google.maps.LatLng(35.658, 139.745),
    zoom: 11
});

// initialize heatmap overlay
var heatmap = new google.maps.visualization.HeatmapLayer({data: heatmapData});

// set overlay
heatmap.setMap(map);