5-java-script-practices-that-will-help-your-teammates-sleep-at-night_8.js

async function initContainer({ children, tagName = 'div' } = {}) {
  const container = document.createElement(tagName)
  if (children) {
    container.appendChild(await children(container))
  }
  return container
}

async function startApp() {
  await initContainer({
    children: (container) => {
      return new Promise((resolve, reject) => {
        const attributes = { src: 'http://www.google.com/abc.png' }
        const elem = document.createElement('iframe')

        Object.entries(attributes).forEach(([attr, value]) => {
          elem.setAttribute(attr, value)
        })

        elem.addEventListener('load', function (evt) {
          resolve(elem)
        })

        elem.addEventListener('error', reject)
      })
    },
  })
}