How to use Babylonjs in Reactjs Application?

Not sure if you have found the answer on your own, however there are several ways now as babylon has matured. There is actually a Node package for using babylon.js with react here: https://www.npmjs.com/package/react-babylonjs

Also there is an install guide for React in Babylon.js in the docs:
https://doc.babylonjs.com/resources/babylonjs_and_reactjs

Hope that helps!

Babylon JS is available as npm package. You can easily build a simple React Component around a canvas and Babylon JS

I have created a minimal example with React+ Babylon:

/* Babylon JS is available as **npm** package.  
You can easily build a simple `React` Component around a `canvas` and Babylon JS
I have created a minimal example with React+ Babylon:
 */
import React, { Component } from "react";
import * as BABYLON from "babylonjs";

var scene;
var boxMesh;
/**
 * Example temnplate of using Babylon JS with React
 */
class BabylonScene extends Component {
  constructor(props) {
    super(props);
    this.state = { useWireFrame: false, shouldAnimate: false };
  }

  componentDidMount = () => {
    // start ENGINE
    this.engine = new BABYLON.Engine(this.canvas, true);

    //Create Scene
    scene = new BABYLON.Scene(this.engine);

    //--Light---
    this.addLight();

    //--Camera---
    this.addCamera();

    //--Meshes---
    this.addModels();

    //--Ground---
    this.addGround();

    // Add Events
    window.addEventListener("resize", this.onWindowResize, false);

    // Render Loop
    this.engine.runRenderLoop(() => {
      scene.render();
    });

    //Animation
    scene.registerBeforeRender(() => {
      boxMesh.rotation.y += 0.01;
      boxMesh.rotation.x += 0.01;
    });
  };

  componentWillUnmount() {
    window.removeEventListener("resize", this.onWindowResize, false);
  }

  onWindowResize = event => {
    this.engine.resize();
  };

  /**
   * Add Lights
   */
  addLight = () => {
    //---------- LIGHT---------------------
    // Create a basic light, aiming 0,1,0 - meaning, to the sky.
    var light = new BABYLON.HemisphericLight(
      "light1",
      new BABYLON.Vector3(0, 10, 0),
      scene
    );
  };

  /**
   * Add Camera
   */
  addCamera = () => {
    // ---------------ArcRotateCamera or Orbit Control----------
    var camera = new BABYLON.ArcRotateCamera(
      "Camera",
      Math.PI / 2,
      Math.PI / 4,
      4,
      BABYLON.Vector3.Zero(),
      scene
    );
    camera.inertia = 0;
    camera.angularSensibilityX = 250;
    camera.angularSensibilityY = 250;

    // This attaches the camera to the canvas
    camera.attachControl(this.canvas, true);
    camera.setPosition(new BABYLON.Vector3(5, 5, 5));
  };

  /**
   * Create Stage and Skybox
   */
  addGround = () => {
    // Create a built-in "ground" shape.
    var ground = BABYLON.MeshBuilder.CreateGround(
      "ground1",
      { height: 6, width: 6, subdivisions: 2 },
      scene
    );
    var groundMaterial = new BABYLON.StandardMaterial("grass0", scene);
    groundMaterial.diffuseTexture = new BABYLON.Texture(
      "./assets/ground.jpeg",
      scene
    );
    ground.material = groundMaterial;

    //Add SkyBox
    var photoSphere = BABYLON.Mesh.CreateSphere("skyBox", 16.0, 50.0, scene);
    var skyboxMaterial = new BABYLON.StandardMaterial("smat", scene);
    skyboxMaterial.emissiveTexture = new BABYLON.Texture(
      "assets/skybox.jpeg",
      scene,
      1,
      0
    );
    skyboxMaterial.diffuseColor = new BABYLON.Color3(0, 0, 0);
    skyboxMaterial.specularColor = new BABYLON.Color3(0, 0, 0);
    skyboxMaterial.emissiveTexture.uOffset = -Math.PI / 2; // left-right
    skyboxMaterial.emissiveTexture.uOffset = 0.1; // up-down
    skyboxMaterial.backFaceCulling = false;
    photoSphere.material = skyboxMaterial;
  };

  /**
   * Add Models
   */
  addModels = () => {
    // Add BOX
    boxMesh = BABYLON.MeshBuilder.CreateBox(
      "box",
      { height: 1, width: 1, depth: 1 },
      scene
    );
    boxMesh.position.y = 1;

    var woodMaterial = new BABYLON.StandardMaterial("wood", scene);
    woodMaterial.diffuseTexture = new BABYLON.Texture(
      "./assets/portal_cube.png",
      scene
    );
    boxMesh.material = woodMaterial;
  };

  render() {
    return (
      <canvas
        style={{ width: window.innerWidth, height: window.innerHeight }}
        ref={canvas => {
          this.canvas = canvas;
        }}
      />
    );
  }
}
export default BabylonScene;

Live Demo:

https://codesandbox.io/s/babylonjs-react-template-w2i1k