siteless.js

// app-shell/main.js
window.app = {
  registerPage(url, cb) {}
  // ...
};

showLoading();

fetch("https://feed.piral.io/api/v1/pilet/sample")
  .then(res => res.json())
  .then(body =>
    Promise.all(
      body.items.map(
        item =>
          new Promise(resolve => {
            const script = document.createElement("script");
            script.src = item.link;
            script.onload = resolve;
            document.body.appendChild(script);
          })
      )
    )
  )
  .catch(err => console.error(err))
  .then(() => hideLoading());

// module/index.jsx
import * as React from "react";
import { render } from "react-dom";
import { Page } from "./Page";

if (window.app !== undefined) {
  window.app.registerPage("/sample", element => {
    render(<Page />, element);
  });
}