I'm not aware of any free code from Trump so far, btw.
Also, when his campaign has tried to code, they fail:
http://qz.com/762424/trumps-campaign-donation-website-used-o...
"A programmer named Shu Uesugi, an engineer at a California company called EdSurge, discovered a major flaw with the way Trump’s website was using jQuery. Instead of downloading the open-source code from GitHub and running it off a server they controlled, the developers who built Trump’s website simply ran the code off GitHub directly, Uesugi found.
While the code’s location might seem like a minor detail, running it off GitHub meant that the person who controlled the code on GitHub could change the code at his whim, and those changes would take hold on Trump’s website. Since GitHub is for open-source projects, it also meant that any user could submit a request to modify the code and impact Trump’s website, if the change was approved by the plug-in’s author, a developer in Lisbon named Igor Escobar."
Then Igor tweeted about how he could have modified it: https://twitter.com/igorescobar/status/766367306662440960?re...
That's how it works for any open source project you use, regardless of where it's been hosted. Unless you review the entire codebase (as well as all changes made in new releases), you're trusting the maintainers' judgement.
Was it sourced from a particular SHA or a "latest" link?
This still wasn't a good idea, but for a different reason - it's relying on the demo at https://igorescobar.github.io/jQuery-Mask-Plugin/ continuing to exist, and continuing to host the plugin at that same path.
Of course, judging candidates' by the code quality of their campaign websites is a rather obscure and somewhat useless pastime.