Loading ESM from regular JS

loadModule.js

function addModule(src) {
  return new Promise((ok, fail) => {
    const script = document.createElement('script');
    const id = `module-${Date.now().toString(16)}-${Math.random().toString(16).slice(2)}`;
    const body = `
import * as myModule from ${JSON.stringify(src)};

document.getElementById(${JSON.stringify(id)}).dispatchEvent(new CustomEvent('moduleloaded', {detail: myModule}));
`;
    script.setAttribute('id', id);
    script.addEventListener('moduleloaded', (event) => ok(event.detail));
    script.onerror = (error) => fail(error);
    script.setAttribute('type', 'module');
    script.innerHTML = body;
    document.head.appendChild(script);
  });
}