Use named import

esbuild.mjs

 const serve = (argv.indexOf('--serve') >= 0);
 
 const options = {
-    //entryPoints: ['src/main.ts'], // AR.default
+    //entryPoints: ['src/main.ts'], // AR.AR
     stdin: {
-        contents: 'import AR from "./main.ts";\nmodule.exports = AR;',
+        contents: 'import { AR } from "./main.ts";\nmodule.exports = AR;',
         resolveDir: 'src',
         sourcefile: 'index.ts',
     },

src/core/viewport.ts

  * Viewport
  */
 
-import AR from '../main';
+import { AR } from '../main';
 import Speedy from 'speedy-vision';
 import { SpeedySize } from 'speedy-vision/types/core/speedy-size';
 import { SpeedyPromise } from 'speedy-vision/types/core/speedy-promise';

src/main.ts

 /**
  * GPU-accelerated Augmented Reality for the web
  */
-export default class AR
+export class AR
 {
     /**
      * Start a new session

src/ui/stats-panel.ts

 import { Tracker } from '../trackers/tracker';
 import { Source } from '../sources/source';
 import { Nullable } from '../utils/utils';
-import AR from '../main';
+import { AR } from '../main';
 
 
 /** Update interval, in ms */