JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdn.rawgit.com/mrdoob/three.js/master/build/three.min.js"></script>

CSS

body {
	  margin: 0;
}

JavaScript

var camera, scene, renderer;
var geometry, material, mesh;
var lastSphere;
var lastGeo;

init();
animate();

function init() {

    camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.01, 10 );
    camera.position.z = 1;

    scene = new THREE.Scene();
    

    renderer = new THREE.WebGLRenderer( { antialias: true } );
    renderer.setSize( window.innerWidth, window.innerHeight );
    renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap; // default THREE.PCFShadowMap

    var light = new THREE.DirectionalLight( 0xffffff, 1, 100 );
light.position.set( 0, 4, 0 ); 			//default; light shining from top
light.castShadow = true;            // default false
//Set up shadow properties for the light
light.shadow.mapSize.width = 1024;  // default
light.shadow.mapSize.height = 1024; // default
light.shadow.camera.near = 1;    // default
light.shadow.camera.far = 20;     // default

scene.add( light );

    
    //Create a sphere that cast shadows (but does not receive them)

geometry = new THREE.SphereBufferGeometry( 0.1, 32, 32 );
material = new THREE.MeshStandardMaterial( { color: 0xff0000 } );
//    geometry = new THREE.BoxGeometry( 0.2, 0.2, 0.2 );
//    material = new THREE.MeshNormalMaterial();

    mesh = new THREE.Mesh( geometry, material );
    mesh.position.y = 0.1;
    mesh.castShadows = true;
    mesh.receiveShadow = false;
    scene.add( mesh );

    var planeGeometry = new THREE.PlaneBufferGeometry( 15, 15, 1, 1 );
var planeMaterial = new THREE.MeshStandardMaterial( { color: 0xffffff, emissive:0x111111 } )
var plane = new THREE.Mesh( planeGeometry, planeMaterial );
plane.position.y = -0.2;
plane.rotation.x = -Math.PI / 2;
plane.receiveShadow = true;
scene.add( plane );


    document.body.appendChild( renderer.domElement );

}

function animate() {

    requestAnimationFrame( animate );

    mesh.rotation.x += 0.01;
    mesh.rotation.y += 0.02;

		var dim = 32;
		var geo1 = new THREE.Geometry();
  ...