future-select.js

const FutureSelect = (selector, parent = document) => {
  let request = null

  return new Promise((resolve) => {
    const select = () => {
      const elements = parent && [ ...parent.querySelectorAll(selector) ] || []

      if (!elements.length) {
        request = requestAnimationFrame(select)
        return
      }

      cancelAnimationFrame(request)
      resolve(elements)
    }

    select()
  })
}