code-example.js

const e = document.createDocumentFragment('div');

const sleep = (ms, caller, ...args) => new Promise(resolve => setTimeout(caller || resolve, ms, ...args));

const waitForHello = async(timeout, elm) => {
    console.log('checking');
    if (elm.innerHTML === 'Hello world') {
        console.log('Value found');
        return;
    } else if ((timeout -= 100) <= 0) {
        throw ('Timed out');
    }
    await sleep(100, waitForHello, timeout, elm);
}

(async ()=>{
  e.innerHTML = 'waiting..'
  //sleep(100, () => e.innerHTML='Hello world');
  try {
      await waitForHello(2000, e);
  } catch (error) {
      throw error;
  }
})()