JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/three.js/r76/three.min.js"></script>

JavaScript

var SCREEN_WIDTH = window.innerWidth - 100;
var SCREEN_HEIGHT = window.innerHeight - 100;

var camera, scene;
var canvasRenderer, webglRenderer;

var container, mesh, geometry, plane;

var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;

init();
animate();

function init() {

    container = document.createElement('div');
    document.body.appendChild(container);

    camera = new THREE.PerspectiveCamera(30, window.innerWidth / window.innerHeight, 1, 100000);
    camera.position.x = 1200;
    camera.position.y = 1000;
    camera.lookAt({
        x: 0,
        y: 0,
        z: 0
    });

    scene = new THREE.Scene();
    
    
      var ambient = 0xf4f4f4;
      var groundMaterial = new THREE.MeshLambertMaterial({
        color: 0xFF0000,
        // map: texture
        // ambient: ambient
      });
      plane = new THREE.Mesh(new THREE.PlaneGeometry(500, 500), groundMaterial);
      plane.rotation.x = -Math.PI / 2;
      plane.receiveShadow = true;
      plane.castShadow = false;

      scene.add(plane);
  
    // LIGHTS
    scene.add(new THREE.AmbientLight(0x666666));

    var light;

    light = new THREE.SpotLight(0xdfebff, 1);
    light.position.set(300, 400, 50);


    light.castShadow = true;
    light.shadowCameraVisible = true;

// ------------------------------------------------------------------------------------

// custom shadow frustum
light.shadow = new THREE.LightShadow( new THREE.PerspectiveCamera( 30, 1, 200, 700 ) );

// shadow camera helper
light.shadowCameraHelper = new THREE.CameraHelper( light.shadow.camera );
scene.add( light.shadowCameraHelper );

// ------------------------------------------------------------------------------------

    scene.add(light);
    
    var boxgeometry = new THREE.CubeGeometry(100, 100, 100);
    var boxmaterial = new THREE.MeshLambertMaterial({
        color: 0x0aeedf
    });
    var cube = new THREE.Mesh(boxgeometry, boxmaterial);
    cube.castShadow = true;
   ...