I know I can preload links in my navbar using preload="insert"
But without this, I want to preload my links on page load. The following is the example from the website that allows preloading links when mouse enters main element. How can I modify this such that my links are preloaded as soon as page is loaded?

up.compiler('link[rel=next]', (link) => {
  return up.on('mouseenter', 'main', () => up.link.preload(link))
})