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, object3D;

init();
animate();

function init() {

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

    scene = new THREE.Scene();

    geometry = new THREE.BoxGeometry( 0.5, 0.2, 0.2 );
    material = new THREE.MeshNormalMaterial();

    mesh = new THREE.Mesh( geometry, material );
    
    object3D = new THREE.Object3D();
    
    object3D.add(mesh);
    
    scene.add( mesh );
    
    camera.lookAt(object3D.position)

    renderer = new THREE.WebGLRenderer( { antialias: true } );
    renderer.setSize( window.innerWidth, window.innerHeight );
    document.body.appendChild( renderer.domElement );
    
    object3D.rotateY(-3.141592653589793);
    
    object3D.updateMatrixWorld();
    
    alert(object3D.rotation.y);
    

}

function animate() {

    requestAnimationFrame( animate );

    renderer.render( scene, camera );

}