JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://unpkg.com/leaflet@0.7.7/dist/leaflet.css">
<script src="https://unpkg.com/leaflet@0.7.7/dist/leaflet-src.js"></script>
<link rel="stylesheet" href="https://unpkg.com/leaflet.markercluster@1.0.0/dist/MarkerCluster.css">
<link rel="stylesheet" href="https://unpkg.com/leaflet.markercluster@1.0.0/dist/MarkerCluster.Default.css">
<script src="https://unpkg.com/leaflet.markercluster@1.0.0/dist/leaflet.markercluster-src.js"></script>
<div id="map"></div>

CSS

#map {
  height: 500px;
}

JavaScript

var map = L.map("map");
L.tileLayer("http://{s}.tile.osm.org/{z}/{x}/{y}.png").addTo(map);

map.setView([48.85, 2.35], 12);
var mcg = L.markerClusterGroup().addTo(map);

for (var i = 0; i < 50; i += 1) {
  L.marker(getRandomLatLng()).addTo(mcg);
}

function getRandomLatLng() {
  return [
    48.8 + 0.1 * Math.random(),
    2.25 + 0.2 * Math.random()
  ];
}