use jQuery CDN

[peterbecich]

The version of jQuery is unchanged, 1.12.4. The CDN (content delivery network) was found here: https://developers.google.com/speed/libraries#jquery

[ysangkok]

What is the advantage of using an additional CDN? Hackage is already served from a CDN. With this change, users that use script blocking extensions like uMatrix would need to allow an additional domain.

[peterbecich]

I hadn't thought of that, but fonts.googleapis.com and jsdelivr.net are already used:

hackage-server/datafiles/templates/Html/candidate-page.html.st

Line 8 in d69f7b6

<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=PT+Sans:400,400i,700"/>

hackage-server/datafiles/templates/hackageCssTheme.st

Line 2 in d69f7b6

<link href="https://fonts.googleapis.com/css?family=PT+Sans:400,400i,700" rel="stylesheet">

hackage-server/src/Distribution/Server/Pages/Template.hs

Line 67 in d69f7b6

googleFontURL = "https://fonts.googleapis.com/css?family=PT+Sans:400,400i,700"

hackage-server/datafiles/templates/Html/package-page.html.st

Line 23 in d69f7b6

<script src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml-full.js" type="text/javascript"></script>

The only two reasons I can think of to merge this PR are:

• reuse jQuery 1.12.4 pre-cached by visiting other websites
• delete lines of code from this repository

[nickburlett]

If you do this, please make it configurable... Having it use a CDN will prevent a hackage mirror from working in an air-gapped system.

[gbaz]

I think if the fonts or mathjax fails that just screws up rendering. We might actually use the jquery functionality for something important to user experience.

[peterbecich]

Closing; I could not make this work with a fallback option.