Tiny DOM ready using requestAnimationFrame first, falling back to readyState.
npm install raf-ready

Fire a callback when the DOM is ready. Prefers requestAnimationFrame and falls
back to document.readyState.
``sh`
npm install --save raf-ready
`js
import ready from 'raf-ready';
ready(() => {
// do something with the DOM.
});
`
Fires callback using available approach.
#### callback
Type: function`
* Google PageSpeed Insight - Optimize CSS Delivery
* How to wait for DOM elements to show up in modern browsers