OneZoom site hangs with in a JavaScript infinite loop if tree_startpoints table is empty

[davidebbo]

When just going to http://127.0.0.1:8000/OZtree/, the browser hangs with high CPU if the tree_startpoints table is empty. This appears to be caused by a bug in uikit, but we could potentially work around on our side.

More specifically, in index.html, we have {{for key in carousel:}}. If carousel is an empty list, we end up with no <li> tags, which makes the uk-slider blow up.

[lentinj]

Wrapping the lot in {{if carousel:}}...{{pass}} seems like the easy way out. With the same applying for the other carousels in the same template.

[davidebbo]

Wrapping the lot in {{if carousel:}}...{{pass}} seems like the easy way out. With the same applying for the other carousels in the same template.

Right, that should do it. I just reported it minimally to uikit as uikit/uikit#5004. Hopefully, if it gets fixed there, we don't need to change our code, other than upgrading uikit.

Getting from the full hang to the minimal repro was ... a fun time!

[davidebbo]

The workaround is to simply add a bogus entry to tree_startpoints. Values can be mostly random, as long as category is homepage_main.

[davidebbo]

Good news: the issue was just fixed in uikit. Keeping this open until we update to a uikit with the fix, which will need to be 3.20.9 or later.

[lentinj]

FWIW switching versions is a case of tweaking here and running ./node_modules/.bin/grunt dev:

OZtree/Gruntfile.js

Line 9 in fa65779

version_uikit = "3.18.3";

But I wouldn't roll it out without testing the UI, particularly the search / advanced search.

[davidebbo]

Thanks @lentinj. Agreed, we'll need to do a good round of testing on the UI. Upgrading is not urgent, as I'm unblocked by adding a dummy tree_startpoints entry.

[hyanwong]

It wouldn't be a bad idea, IMO, to have {{if carousel:}}...{{else}}Sensible text{{pass}} on the homepage anyway. It can help point the way for anyone installing a new version without stuff in the DB (which includes out future selves).