three.js/manual/examples/threejs-responsive.js

import * as THREE from 'three';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );
	renderer.useLegacyLights = false;

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 5;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.z = 2;

	const scene = new THREE.Scene();

	{

		const color = 0xFFFFFF;
		const intensity = 3;
		const light = new THREE.DirectionalLight( color, intensity );
		light.position.set( - 1, 2, 4 );
		scene.add( light );

	}

	const boxWidth = 1;
	const boxHeight = 1;
	const boxDepth = 1;
	const geometry = new THREE.BoxGeometry( boxWidth, boxHeight, boxDepth );

	function makeInstance( geometry, color, x ) {

		const material = new THREE.MeshPhongMaterial( { color } );

		const cube = new THREE.Mesh( geometry, material );
		scene.add( cube );

		cube.position.x = x;

		return cube;

	}

	const cubes = [
		makeInstance( geometry, 0x44aa88, 0 ),
		makeInstance( geometry, 0x8844aa, - 2 ),
		makeInstance( geometry, 0xaa8844, 2 ),
	];

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	function render( time ) {

		time *= 0.001;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		cubes.forEach( ( cube, ndx ) => {

			const speed = 1 + ndx * .1;
			const rot = time * speed;
			cube.rotation.x = rot;
			cube.rotation.y = rot;

		} );

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();