structured-clone.js

async function structuredClone(obj) {
  return new Promise(resolve => {
    const { port1, port2 } = new MessageChannel();
    port2.onmessage = evt => resolve(evt.data);
    port1.postMessage(obj);
  });
}

// Usage
const a = { a: 1, b: 2, c: [1, 2, 3], d: { person: { name: "oliver" } } };
const { d } = await structuredClone(a);
console.log(d); // <= {person: {name:"oliver"}}