light check three.js

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/87/three.min.js"></script>

JavaScript

var camera, scene, renderer, mesh, material, canvas;
init();
animate();

function init() {
    // Renderer.
    renderer = new THREE.WebGLRenderer({preserveDrawingBuffer: true, antialias : true});
    //renderer.setPixelRatio(window.devicePixelRatio);
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.shadowMap.enabled = true;
    // Add renderer to page
    document.body.appendChild(renderer.domElement);

    // Create camera.
    camera = new THREE.PerspectiveCamera(70, window.innerWidth / window.innerHeight, 1, 1000);
    camera.position.z = 400;

    // Create scene.
    scene = new THREE.Scene();

    // Create material
    material = new THREE.MeshPhongMaterial({color:0xFF0000});

    // Create cube and add to scene.
    var geometry = new THREE.BoxGeometry(200, 200, 200);
    mesh = new THREE.Mesh(geometry, material);
    mesh.castShadow = true;
    //mesh.receiveShadow = true;
    scene.add(mesh);

    // Create ambient light and add to scene.
    var light = new THREE.AmbientLight(0x404040); // soft white light
    scene.add(light);

    // Create directional light and add to scene.
    //var directionalLight = new THREE.DirectionalLight(0xffffff);
    //directionalLight.position.set(1, 1, 1).normalize();
    //scene.add(directionalLight);
    
    var spotLight = new THREE.SpotLight( 0xffffff, 1.0 );
    spotLight.position.set( 0, 500, 0 );
    spotLight.castShadow = true;
    scene.add(spotLight);
    
    // Ground plane
    var groundGeo = new THREE.PlaneBufferGeometry(10000, 10000);
    var groundMat = new THREE.MeshPhongMaterial({
      color : 0xffffff,
    });
    var ground = new THREE.Mesh(groundGeo, groundMat);
    ground.rotation.x = -Math.PI / 2;
    ground.position.y = -100;
    ground.receiveShadow = true;
    scene.add(ground);

    // Add listener for window resize.
    window.addEventListener('resize', onWindowResize, false);


    
    //assumes wegbGL renderer
   ...