Prerender EAGERNERSS

[giorgiopellegrino]

Hello @addyosmani and @XhmikosR,

I have implemented a key feature for my company that allows prerendering URLs with an eagerness configuration. The fallback is a prefetch triggered on mouseenter when the eagerness property is set to "moderate" or "conservative."

Main changes:

1. Added functionality to prefetch elements corresponding to the URL upon the mouseenter event.
2. Added the handling of the eagerness attribute of the script in the speculation rules.
3. The prerender fallback for devices that do not handle speculation rules has been implemented by adding prefetch, triggered at the mouseenter, if the eagerness mode is ‘moderate’ or ‘conservative’.
4. All the functions added for prefetch and prerender are available in the listen function to options property, and they will only be executed when elements enter the viewport: options.onlyOnMouseover, options.eagerness

window.addEventListener('load', () => {
  quicklink.listen({el, priority, onlyOnMouseover,
                    prerender, eagerness});
});

quicklink.prefetch(url, isPriority, onlyOnMouseover);

quicklink.prerender(url | [urls], eagerness);

I hope these changes will be appreciated, as they are currently in use across our e-commerce platforms.

Thank you very much.

Giorgio Pellegrino.

cc @gilbertococchi