Feature: rewrite URLs so that `%3D` chars are rendered as `=`

[erikmd]

Related user(s):

@erikmd

Related issue(s) or PR(s):

No response

Related project scope(s):

web-app UI

The problem:

When opening an exercise in a dynamic learn-ocaml server, the = chars are unexpectedly rendered as %3D:

• http://localhost:8080/exercises/tp1/#tab%3Dreport

Wanted solution:

It would be nice to keep the = chars as is thanks to URL rewriting (if possible):

• http://localhost:8080/exercises/tp1/#tab=report

Considered alternatives:

No response

Additional context:

No response

[Plictox]

If you agree I think I can do the same thing for the '&' character, as in this URL : http://localhost:8080/exercises/mooc/week1/seq3/ex1/#tab%3Dtext%26prelude%3Dshown

[erikmd]

@Plictox yes! that looks good.

[erikmd]

@Plictox FYI I did a few searches on MDN, and I have some news:

1. The culprit in learn-ocaml's code base is this code:

learn-ocaml/src/utils/js_utils.ml

Lines 1201 to 1204 in 1584a08

	let set_fragment args =
	let pairs = List.map (fun (n, v) -> n ^ "=" ^ v) args in
	let fragment = String.concat "&" pairs in
	Url.Current.set_fragment fragment

2. Replacing Url.Current.set_fragment fragment with Dom_html.window##.location##.hash := Js.bytestring fragment solves the issue.

3. FTR, the location.hash is documented at https://developer.mozilla.org/en-US/docs/Web/API/Location/hash

4. There was an old bug in Firefox w.r.t. encoding/decoding only for the getter (see e.g. https://stackoverflow.com/questions/1703552/encoding-of-window-location-hash ), but AFAICT, it is unneeded to manually url-encode also the URLs for the setter.

So I assign @AltGr and myself for now, we'll see at our next maintainer telco (end-May) if we propose a patch upstream to simplify Url.Current.set_fragment