index.js

import React from 'react';
import ReactDOM from 'react-dom';
import * as serviceWorker from './serviceWorker';
import createWorker from 'offscreen-canvas/create-worker';

import App from './App';
import { Store } from './Store';

ReactDOM.render(
  <Store.Provider>
    <App />
  </Store.Provider>,
document.getElementById('root'));

const workerUrl = document.querySelector('[rel=preload][as=script]').href;
const canvas = document.querySelector('canvas');

export const worker = createWorker(canvas, workerUrl, e => {
  console.log(e);
});

serviceWorker.unregister();

webgl.chunk.js

(window["webpackJsonp"] = window["webpackJsonp"] || []).push([["webgl"],{

/***/ "./node_modules/offscreen-canvas/inside-worker.js":
/*!********************************************************!*\
  !*** ./node_modules/offscreen-canvas/inside-worker.js ***!
  \********************************************************/
/*! no static exports found */
/***/ (function(module, exports) {

module.exports = function (listener) {
  if (typeof window !== 'object') {
    onmessage = listener;
    return {
      post: function (a, b) {
        postMessage(a, b);
      },
      isWorker: true
    };
  } else {
    var randomId = document.currentScript.dataset.id;
    var connection = window[randomId];
    delete window[randomId];
    connection.worker = listener;
    setTimeout(function () {
      connection.msgs.forEach(function (data) {
        connection.worker({
          data: data
        });
      });
    }, 1);
    return {
      post: function (data) {
        connection.host({
          data: data
        });
      },
      isWorker: false
    };
  }
};

/***/ }),

/***/ "./src/webgl.worker.js":
/*!*****************************!*\
  !*** ./src/webgl.worker.js ***!
  \*****************************/
/*! no exports provided */
/***/ (function(module, __webpack_exports__, __webpack_require__) {

"use strict";
__webpack_require__.r(__webpack_exports__);
/* harmony import */ var offscreen_canvas_inside_worker__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! offscreen-canvas/inside-worker */ "./node_modules/offscreen-canvas/inside-worker.js");
/* harmony import */ var offscreen_canvas_inside_worker__WEBPACK_IMPORTED_MODULE_0___default = /*#__PURE__*/__webpack_require__.n(offscreen_canvas_inside_worker__WEBPACK_IMPORTED_MODULE_0__);

offscreen_canvas_inside_worker__WEBPACK_IMPORTED_MODULE_0___default()(e => {
  console.log(e);

  if (e.data.canvas) {
    alert('loaded');
  }
});

/***/ })

},[["./src/webgl.worker.js","runtime~webgl"]]]);
//# sourceMappingURL=webgl.chunk.js.map

webgl.worker.js

import insideWorker from 'offscreen-canvas/inside-worker';

insideWorker(e => {
  console.log(e);
  if (e.data.canvas) {
    alert('loaded');
  }
});