Normalize URLs before checking the `toPrefetch` set about quicklink

[addyosmani]

This is a great catch. Nice work highlighting the normalization issue, @mathiasbynens ❤️ Given URL() has pretty decent cross-browser support, I'm happy for us to use your suggested change in some form. We probably want to sanity check if normalization should happen elsewhere in index.mjs.

Do you want to PR a fix? If not, happy to patch directly :)

[lukeed]

Nothing gets added to toPrefetch when you pass in an options.url list. The prefetcher only looks to remove Set entries – additions are made thru the "scraped" links which are already normalized as you mentioned.

That said, we should still probably normalize so that the prefetch itself can send valid requests. Eg, fetch('https:\\www.google.com/') will fail.

IMO, normalization should happen here: https://github.com/GoogleChromeLabs/quicklink/blob/master/src/index.mjs#L37

It'll be redundant for the "scraped" links, but it avoids adding a new function 😇

[addyosmani]

@lukeed Hah. Avoiding the addition of a new function is fair. Were you thinking of normalization around L37 looking similar to this?

function prefetcher(url) {
  const nURL = new URL(url).toString();
  toPrefetch.delete(nURL);
  prefetch(nURL, observer.priority);
}

[lukeed]

I blame Jason 🙃

Was thinking this:

function prefetcher(url) {
 toPrefetch.delete(url);
 prefetch(new URL(url).toString(), observer.priority);
}

Since anything that makes its way into toPrefetch is already normalized. If we introduce some way for option.urls to coexist within the Set, then yes, the whole Set has to be normalized on entry and/or removal

---

Edit: We can also just do prefetch(new URL(url), priority) since fetch() will accept an URL or string & I just discovered that XHR will also work with a URL instance. 🎉

[addyosmani]

Closed by #37. Thanks again!