JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://api.mapbox.com/mapbox.js/v2.3.0/mapbox.css">
<link rel="stylesheet" href="https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/MarkerCluster.css">
<link rel="stylesheet" href="https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/MarkerCluster.Default.css">
<script src="https://api.mapbox.com/mapbox.js/v2.3.0/mapbox.js"></script>
<script src="https://api.mapbox.com/mapbox.js/plugins/leaflet-markercluster/v0.4.0/leaflet.markercluster.js"></script>
<div id='map'></div>

CSS

body { margin:0; padding:0; }
  #map { position:absolute; top:0; bottom:0; width:100%; height:400px; }

JavaScript

var addressPoints = [
			[-37.8210922667, 175.2209316333, '<div class="map-post"><div class="map-post-thumb"><img src="images/grid/post245x150-1.jpg" alt="post245x150-1"></div><div class="map-post-des"><div class="map-post-title"><h5>3as Bed Detached House</h5></div><div class="map-post-address"><p><i class="fa fa-map-marker"></i> Brighton, The City of Brighton</p></div></div></div>'],
			[-37.8210819833, 175.2213903167, "3",'images/pins/hotels.png'],
			[-37.8210881833, 175.2215004833, "3A",'images/pins/food.png'],
			[-37.8211946833, 175.2213655333, "1"],
			[-37.8209458667, 175.2214051333, "5"],
			[-37.8208292333, 175.2214374833, "7"],
			[-37.8325816, 175.2238798667, '<div class="map-post"><div class="map-post-thumb"><img src="images/grid/post245x150-1.jpg" alt="post245x150-1"></div><div class="map-post-des"><div class="map-post-title"><h5>3as Bed Detached House</h5></div><div class="map-post-address"><p><i class="fa fa-map-marker"></i> Brighton, The City of Brighton</p></div></div></div>'],
			[-37.8315855167, 175.2279767, "454"],
			[-37.8096336833, 175.2223743833, "176"],
			[-37.80970685, 175.2221815833, "178"],
			[-37.8102146667, 175.2211562833, "190"],
			[-37.8088037167, 175.2242227, '<div class="map-post"><div class="map-post-thumb"><img src="images/grid/post245x150-1.jpg" alt="post245x150-1"></div><div class="map-post-des"><div class="map-post-title"><h5>3as Bed Detached House</h5></div><div class="map-post-address"><p><i class="fa fa-map-marker"></i> Brighton, The City of Brighton</p></div></div></div>'],
			[-37.8112330167, 175.2193425667, "210"],
			[-37.8116368667, 175.2193005167, "212"],
			[-37.8194342167, 175.22322975, "9"]
		];

L.mapbox.accessToken = 'pk.eyJ1IjoibGlzdGluZ3BybyIsImEiOiJjaWxhaGZjNWgwMDB1d25tMm1uZThub2wyIn0.UF5krbL-hVDhMcARAZmDGQ';
    var map = L.mapbox.map('map', 'mapbox.streets')
        .setView([-37.82, 175.215], 14);

    var markers = new L.MarkerClusterGroup();

    for (var i = 0; i < addressPoints.length; i++) {
   ...