docs: Version switcher is broken / misleading

[bnb]

Currently if you try to switch to other semver major versions of the same docs on the docs site, you get extremely inconsistent results. Questions I had as I was going throught

As an example, here are the HTTP/2 docs:

v8.x

v9.x (where is v8.x?)

v10.x (where is v8.x, and why wasn't this doc listed on the v8.x or v9.x docs pages?)

v11.x (why wasn't this listed on any of the other pages?)

I experienced this in a few other docs pages as well.

[addaleax]

I’m not sure who to ping for this, but I’m sure @rubys or @vsemozhetbyt would know?

[richardlau]

Not sure of the answer to all of the questions, but at least for:

v11.x (why wasn't this listed on any of the other pages?)

I think we need to add to:

node/tools/doc/html.js

Lines 403 to 416 in 2cab511

	function altDocs(filename, docCreated) {
	const [, docCreatedMajor, docCreatedMinor] = docCreated.map(Number);
	const host = 'https://nodejs.org';
	const versions = [
	{ num: '10.x' },
	{ num: '9.x' },
	{ num: '8.x', lts: true },
	{ num: '7.x' },
	{ num: '6.x', lts: true },
	{ num: '5.x' },
	{ num: '4.x' },
	{ num: '0.12.x' },
	{ num: '0.10.x' }
	];

and get it backported to all non-EOL release lines. I'll raise a PR (edit: #23980).

[refack]

So AFAICT it depends on what was backported when...
I think since v8.0.0 did not have HTTP/2 our inference logic fails.
Also we have the limitation that once a doc version was built it is static. ATM we don't have a way to update it of newer versions.

[vsemozhetbyt]

If we want this to work for backported docs, maybe we need to move this from doctools to some webpage dynamic script.

[sagitsofan]

It is possible, but i am not sure it is worth all the hard work for that small feature.
Maybe just fix it manually in the backported docs?

[Trott]

The cause here is a bug in tools/doc/html.js. PR coming shortly.

[Trott]

Proposed fix in #24638

[Trott]

Fix landed in 6f64cda. Not sure why this didn't auto-close....